An acorn-tongued worm, a lancelet, a lamprey, a shark, and a perch. If individual specimens are not available, the pupil's text-book and charts are to be used.

Observations.

Acorn-tongued worm:

Notice the very simple form and structure of the symmetrical body, the "proboscis," the collar surrounding the neck with its simple rod of cartilage, the marks of internal gills and gill slits extending some distance along the body, and the presence or absence of sense organs. The acorn-tongued worm (Balanoglossus) lives in the sand of the seashore and in shallow water in temperate and tropical regions.

Lancelet:

Observe the form of the body, of the fin, and of the mouth; note the presence or absence of sense organs, and find out the number of gills or gill slits. The lancelet (Amphioxus) is similar in habit to the acorn-tongued worm. By day it lies buried with only the mouth exposed, but at night it swims actively about. It is somewhat more confined to the tropics.

Lamprey:

Observe here also the primitive or unspecialized form of the body, of the fin, of the jawless mouth, the number of gill slits, and the sense organs.

Shark:

Examine the body, noting its form and differentiation into regions, its covering, its fins, mouth, gill slits, and sense organs.

Perch:

If you have not already studied the bony fish, the points suggested for the shark will be sufficient for this exercise.

In each case, find out the condition of the skeleton.

Questions.

1. Which of these animals seem most simple in form, and which most complex? Give a reason for your answer.
2. Give the stages which show how the fold of skin develops into separate fins.
3. How does the number of gills and gill slits change in the series? (Give definite numbers.) How may the reduction in the number of gills be compensated for in the amount of surface exposed for the exchange of gases in breathing?
4. How is protection afforded the delicate structure of the gills in the final form?
5. Give the stages in the formation of a definite, symmetrical mouth with jaws of equal size.
6. The presence of sense organs may be taken to indicate that there is an organ of control, or brain. How is the development of this organ like or unlike that of the other structures in the series?
7. For the developing brain and nervous system what protection and support is afforded in each case?

The foregoing questions may be answered in tabular form by arranging the names of the animals in a line and the questions in a column.

Suggested drawings.

1. Acorn-tongued worm, × 1.
2. Lancelet, × 1.
3. Lamprey, × ½.
4. Shark: 1, head as far as the pectoral fins; 2, the tail.
5. Perch, as directed for shark.

B. Studies of Amphibia

Progress from Water-living Animals to Land-living Animals

The Living Frog or Toad

The Body.

1. Contrast the body of the frog with that of the fish as to regions, shape, and compactness. How do you account for the differences?

Locomotion.

1. What kinds of locomotion can a frog use? Why is it difficult for a frog to crawl or walk? How far can a frog jump? How are swimming and jumping accomplished? What do you think is the use of the "hump" on the back?
2. Identify in the legs the thigh, shank, ankle, foot, toes, and web, and in the arm, the upper arm, forearm, wrist, hand, and fingers. State in detail the differences in structure and in position between the fore and hind limbs. How do you account for these differences?

Feeding.

1. Induce a frog or toad to eat by dangling food, such as a piece of raw meat or meal worms, small earthworms, etc., before it. How does it seize the food? What will it eat? How is the mouth adapted to this manner of feeding?

Respiration.

1. The frog has no diaphragm, and therefore no chest cavity; watch very carefully the movements of the mouth, the nostrils, the throat, and the sides of the body to determine how the problem of breathing (how the air is gotten into and out of the lungs) without a diaphragm is solved. Write a detailed account of the frog's method of breathing which shall explain just how the air is forced into the lungs.
2. What would be the effect of propping open the mouth of the frog? Why? Does the frog breathe in the usual manner while under the water? If not, how do you explain its ability to remain under water for a long period of time?

Sense Organs.

1. Investigate the efficiency of the five special senses in the frog by devising experiments to test each sense; as, for example, giving a frog its liberty on the floor and trying to catch it again, to test the sense of sight. Write an account of your experiments and their results. Which of the senses is best developed? Give reasons for your answer.
2. Compare the eye of the frog with respect to its shape, movements, parts, and protective structures with that of the fish. In what respects are they similar? in what respects different? Why should they differ?
3. Where are the frogs' ears located? What do you think of the efficiency of an eardrum situated on the surface of the body? Why?
4. The frog has certain other responses. Try turning the jar or cage containing a frog around to face the frog in another direction. What happens? How do you explain this response on the basis of use? What other responses have you noticed?

Protection.

1. Has the frog an exoskeleton? Describe the color scheme of the frog and explain how it may be protective. Why are frogs brighter in spring than in fall?
2. Why do frogs usually live near water? Do they ever leave the vicinity of streams? If so, when?

Summary.

In what ways is the frog adapted to water life? In what ways to life on land? In what respects do toads differ from frogs?

The Frog's Mouth

Tongue.

Draw it forward until the free end extends from the mouth and is outspread; observe its form, extent, and attachment.

Teeth.

Find those on the jaws and on the roof of the mouth.

Nostrils.

Push the bristle inward through a nostril to determine its direction and extent.

Vocal cords.

These form a hard white mass in the floor of the mouth, well back behind the tongue.

Glottis,

the slit inclosed between the vocal cords, opening into the trachea.

Esophagus,

the passage to the stomach, at the posterior end of the mouth.

Eustachian tubes,

small passages outward to the ears at the junction of the upper and lower jaws.

Questions.

1. Describe the probable action of the frog's tongue in catching a bug.
2. What advantage can you ascribe to the peculiar mode of attachment of the tongue?
3. Of what use is the notch in the inner end of the tongue? (Note its position when the tongue lies at rest in the mouth.)
4. If the frog chewed its food, how would the existing structure of the nostrils be very inconvenient?
5. Recall either the frog's habit of feeding or the structure of the nostrils. Do you think the nostrils are of much service in smelling? State the reason for your answer.
6. Of what use are the vocal cords and why are they so muscular? Consider their use in sound making and also their condition during swallowing.
7. Of what use are the teeth? Recall the form and use of the fish's teeth.

Suggested drawings.

1. The mouth, wide open and with tongue extended.
2. A diagram showing the path of air and of food through the frog's mouth.

The Organs of Digestion, Absorption, and Excretion

Placing the frog on its back, with forceps firmly grasp the skin of the abdomen and the muscles beneath, just in front of the hind legs, and with the scissors cut straight forward in the middle line until the floor of the mouth is reached; this will separate the arms. Care must be taken not to cut too deeply, but this may be avoided by keeping the skin uplifted. Now cut sidewise in front of each hind leg in order that the body wall may be laid aside. Under the arms the heart will be seen; it will be studied as a part of the circulatory system.

Identify the following organs:—

Liver,

the large red or brown mass, consisting of several divisions and lying close up under the arms.

Bile sac,

small, green, and between the liver lobes.

Alimentary canal.

1. Mouth.
2. Esophagus.
3. Stomach, the elongated, light-colored, firm, and muscular portion.
4. Small intestine, a slender, more or less closely coiled, tubular portion.
5. Large intestine, a thin-walled enlargement at the posterior end of the canal.
6. Duodenum. This is a muscular portion of the small intestine immediately following the stomach, against which it is folded.

Pancreas,

a yellowish, pulpy mass lying in the fold between the stomach and the duodenum.

Spleen,

a dark red globule, usually smaller than a pea, lying nearly free among the folds of the small intestine.

Fat bodies,

yellow fringe-like structures, sometimes found near the stomach.

Kidneys,

a pair of elongated dark red organs, behind the spleen and against the back. Note their numerous blood vessels. Possibly the ureters, or urinal ducts, can be discovered and traced to their junction with the bladder, a clear membranous sac in the posterior extremity of the body cavity.

Peritoneum,

a thin membrane lining the body cavity and attaching the vital organs to the backbone.

Note.—Specimens secured in late fall, winter, or early spring may contain, if female, a large number of dark-colored eggs; or if male, two white testes, located near the kidneys and similar to them in form, though smaller.

Questions.

1. Name the parts of the frog's alimentary canal.
2. Name the glands or organs which are accessory to the canal.
3. How long is the esophagus? How does the presence or absence of a neck affect the esophagus?
4. How does the thickness of the stomach wall compare with that of the intestine, and how do you account for the difference?
5. Measure the length of the trunk of the frog's body and that of the outstretched alimentary canal. How many times the length of the one is that of the other? How does this ratio compare with that of an herbivorous animal? (The sheep's food canal is about thirty-two times the length of its body.)
6. What is the color of the bile, as seen through the walls of the bile sac? This color is characteristic of carnivorous animals; in herbivorous forms it is yellow. Find its color in some omnivorous form, as man.
7. Name the organs concerned in excretion.
8. What holds the internal organs in place, and from what are they suspended?
9. The spleen is called a "ductless gland." Give its function, and explain why a duct is not necessary to it.
10. Since the frog swallows its food alive and entire, what work must the stomach do? What digestive organs would be absent from the mouth, or else poorly developed?
11. Since the frog is carnivorous, what digestive ferments are probably present, and what ones absent from the alimentary canal?
12. Fat bodies are largest in the fall, and are rarely found in the spring. How can you account for this?
13. When through with the general study of the alimentary canal, you may open the stomach by cutting it lengthwise. Describe the character of the stomach lining as to folds and villi, stating the advantage of each being present and the reason for the direction of the folds. Tell how the food is propelled onward through the alimentary canal. Give the scientific name for this action.

Suggested drawings.

1. The viscera (internal organs) undisturbed.
2. The alimentary canal extended.
3. The excretory system.

The Organs of Circulation and Respiration of the Frog

Pericardium,

a membrane that surrounds the heart and, in the case of the frog, separates the body cavity into two portions, the abdomen and the pericardial chamber.

Heart,

lying between the shoulders and in front of the false diaphragm. It is conical in form and composed of three chambers.

Ventricle,

the pink, conical, and muscular portion of the heart, pointing backward and outward.

Auricles,

right and left. These are anterior and dorsal to the ventricle, thin, membranous, and dark-colored.

Arterial trunk,

the single large blood vessel, usually empty of blood, and white. Note its origin and trace it as far as possible, at least until you see it divide to encircle the throat.

Sinus venosus,

a large membranous sac dorsal to the heart and connected with the right auricle.

Lungs,

two small oblong, pink, spongy sacs, lying between and behind the shoulders.

Questions.

1. Of how many chambers does the frog's heart consist? Name them, and describe them as to size, color, and structure.
2. Which chamber receives blood from the body, and which receives blood from the lungs?
3. Name the large arteries and give the regions which they supply. Name the large veins and give the regions from which they come.
4. Describe the lungs as to size, both when inflated and when uninflated. Describe their color; entirety or subdivision; texture.
5. In the inflated lung, notice the interior partitions or chambers, which are called vesicles. How do they affect the amount of surface exposed for gas exchange in breathing?
6. Measuring the lung collapsed and again when inflated, calculate its approximate volume in each case and state how much air it may take in during an inspiration.
7. Describe the diaphragm and state its probable use as a factor in respiration or as a partition.

Advanced questions.

1. Apparently the pure and the impure blood must commingle upon entering the single ventricle, but by a simple device this scarcely occurs. How would such commingling affect the purity of the blood as it reached the tissues, and hence affect waste removal, oxidation, body temperature, activity, and intelligence?
2. What are the chambers of the fish's heart? of the mammalian (human) heart? How may the heart of the frog be regarded as intermediate between these others? How and where might the growth of a partition within it bring about the higher structure? (This actually occurs in certain reptiles.)
3. The lungs are said to be outgrowths of the alimentary canal. Explain how their connection would tend to show this.

Suggested drawings.

1. The heart and lungs in their normal position.
2. The circulatory system, as seen in the injected specimen.
3. A copy of the diagram or model of the circulatory system.
4. A diagram of the respiratory tract from the nostrils to the lungs, by arrows showing the course of the air.

The Nervous System of the Frog

B. Spinal cord, extending along the spine, giving rise to nerves.

C. Spinal nerves, ten pairs of nerves which are connected with the cord through dorsal (sensory) and ventral (motor) roots, and which penetrate the body and its appendages. The first enters the neck; the second and third join and enter the arm; the fourth to sixth penetrate the skin and muscles of the trunk; the seventh to ninth join by a plexus to form the sciatic nerve which supplies the leg, and the tenth enters the posterior portion of the body.

Questions.

1. Which lobes of the brain are paired? Give at least two possible causes or reasons for their double structure.
2. The optic lobes are connected with the eyes. Compare their size with that of the other parts. Of how much use do you think they are to the frog?
3. If folds or convolutions in the surface of the cerebrum indicate intelligence, thoughtfulness, or mind, what do you infer as to the frog's mental condition and power to think?
4. Has the frog brain or "brains"? Explain.
5. Name several things done by an animal's brain.
6. Which of the spinal nerves are specially large? Why should they be large?
7. What advantages are there in the frog's having a dorsal nerve cord instead of a ventral one, as the earthworm has?

   What would be the effect of cutting or breaking the dorsal root of a spinal nerve? the ventral root? the entire spinal cord? How do you explain the convulsions of the brainless (beheaded) chicken or frog?

8. What kinds of impulses originate outside of the nerve center, and what kinds in the center?
9. Sensations reach the cord and brain through the dorsal root of the spinal nerve. What kinds of messages travel through the ventral root, and in what direction do they go?

Suggested drawings.

1. The brain.
2. The spinal cord and its nerves.
3. The nervous system.
4. A diagram of the cord and its nerves, showing the kinds and the directions of the nerve impulses.

The Endoskeleton of the Frog

1. Cervical vertebra, the first vertebra, supporting the skull.
2. Dorso-lumbar vertebræ, vertebræ with small lateral processes.
3. Sacrum, the ninth vertebra, bearing extra long lateral processes or "arms."
4. Urostyle, the last vertebra, lying in the median line, a long, slender, blade-like bone, really formed by the fusion of several vertebræ.

C. Vertebra:—

1. Centrum, the solid, nearly circular portion.
2. Lateral process, one of the paired projections, extending outward on either side.
3. Neural spine, the single projection, extending toward the dorsal side.
4. Neural arch, formed largely by a connection between the lateral process and the neural spine. The arch above and the centrum below inclose the neural canal.

D. Pectoral, or Shoulder, Girdle:—

1. Sternum, the "breastbone," extending along the median ventral line.
2. Coracoid, a heavy bone extending from the sternum sidewise to support the arm.
3. Clavicle, the "collar bone," a light bone in front of the coracoid.
4. Scapula, the "shoulder blade," a broad, thin bone which arches around to the dorsal side.

E. Pelvic, or Hip, Girdle:—

1. Ilium, a long, slender, curved bone, with its mate uniting to form an inverted "wishbone"; it is joined to the sacrum.
2. Pelvis, the region of the socket at the junction of the ilia.

F. Fore Leg, or Arm:—

1. Humerus, the single bone of the upper arm.
2. Radius, the bone of the lower arm on the thumb side; in the frog united to the ulna.
3. Ulna, the bone of the forearm opposite the radius.
4. Carpals, small bones of the wrist.
5. Metacarpals, a single series of long bones forming the palm of the hand.
6. Phalanges, the bones of the fingers and thumb (singular phalanx).

G. Hind Leg:—

1. Femur, the thigh bone, next to the body.
2. Tibia, the larger bone of the lower leg on the inner side; in the frog united to the fibula.
3. Fibula, the smaller bone of the lower leg.
4. Tarsals, the small bones of the instep.
5. Metatarsals, the long bones of the instep.
6. Phalanges, the bones of the toes.

Questions.

1. Whereabouts in the frog has nature made an attempt to inclose delicate or vital structures in bony cases?
2. Examining the inside of the mouth, find the teeth. Judging from their size and structure, of what use are these teeth?
3. What advantages can you see in having the arms and legs attached to girdles instead of having them fastened directly to the vertebral column? How has their development affected the shape of the trunk, as opposed to that of the fish?
4. Make a comparison of the two girdles as to their attachment to the spine and their consequent rigidity or freedom of movement.
5. How many vertebræ are there in the spinal column? What advantage can you see in having the column composed of many small vertebræ instead of a few large ones? Enumerate those having a special form or structure, and state the use of each.
6. On the vertebræ notice any irregularities, prominences, or roughenings. For what are such bones better adapted than smooth bones would be?
7. How is the frog's humping permitted? How are the urostyle and the pelvis connected, if at all? Has this any effect on motion? (See living frog.)
8. In parallel columns, keeping corresponding parts in a line, tabulate the bones of the fore and hind limbs.
9. State how extra length has been attained in the hind leg, and give the purpose or the result of this lengthening.
10. In the forearm notice the fusing of the radius and ulna. How would these parts act in rotating the hand, as compared with your own, where they are free? Compare also the tibia and fibula. Where in the frog's leg is turning made possible by the use of parallel bones?
11. Compare the frog's hand and foot as to number of fingers and toes; as to length and spread. Have any fingers or toes only two phalanges?
12. How would an inner skeleton affect the growth and the size of an animal, as compared with an outer skeleton, like the clam's?
13. How would the lack of an outer skeleton influence sensitiveness, activity, and intelligence?

Suggested drawings.

1. The skull and trunk, with appendages of one side.
2. Each set of bones separately, as the skull, the column, etc.

Comparative Study of Amphibia

Amphibia: A General Review and Library Exercise

1. The usefulness of the American toad.
2. The breeding habits of the common frog; of the Surinam toad; of the obstetrical toad; of the "smith."
3. The development of the axolotl.
4. The habits of the tree frogs and their variable coloration.
5. The croaking of frogs and of toads.
6. The flying frog of Ceylon.
7. The distribution and habits of the hellbender; of the mud puppy; of the Congo "snake."
8. The general absence of the amphibia from arid regions.
9. Frog farming for city markets.
10. Protective devices of various amphibia.
11. Toads and warts.
12. The homing and water instincts of toads.
13. Hibernation, seasonal or prolonged, of toads and frogs.
14. The changes in the respiratory and circulatory system during metamorphosis.
15. Ontogeny and phylogeny, as illustrated by amphibia.
16. The structural defects which would prevent an ambitious frog from becoming a highly trained and skillful animal.
17. The classification of amphibia, with examples.
18. The kinds of frogs and toads found in the region where you live.

C. Studies of Living Reptiles

Showing Diversity of Adaptation among closely related Animals

The Snake

1. What is the shape? What regions are present? How do you distinguish between the trunk and the tail? Has the tail any use? What are the advantages of a body without limbs?
2. Describe the snake's path in locomotion. How is locomotion accomplished? Is the absence of limbs a hindrance to the animal in its locomotory activity?
3. Describe the appearance and movements of the tongue. Of what use are these movements of the tongue?
4. What evidence is there that the snake breathes with lungs?
5. What sense organs do you find? Compare the ears and eyes with those of the frog. What explains the peculiar staring appearance of the eyes?
6. What is the color scheme? Does it appear to be protective? If so, how?
7. Of what does the exoskeleton consist? How are the scales arranged? What variations in the size of the scales do you find? What special use have some of the scales? How fitted for this? How does a snake moult? Appearance before and after moulting.

The Florida Lizard

1. Describe the body as to regions and shape. Is the tail of use?
2. What are the lizard's locomotory abilities? How is it fitted for living in trees?
3. Feed the lizard flies or meal worms and describe its method of capturing them.
4. Compare the lizard's respiration and sense organs with those of the snake and frog.
5. What is the usual color of the lizard? What have you discovered about its power to change colors? How may this be of use to it?
6. Of what does the exoskeleton consist? Is the entire body covered? How are the scales arranged? How does the lizard moult?

The Turtle

1. In what important ways does the body of the turtle differ from those of the snake and lizard?
2. What methods of locomotion has the turtle? For which method is it best fitted? How? Why are its movements in water so much less clumsy than on land? (Compare weight on land with weight in water.) Compare the efficiency of the locomotion of a turtle with that of a lizard and suggest a reason for the difference.
3. What do turtles eat while in the laboratory? Since turtles have no teeth, how can they bite off their food?
4. What can you discover with respect to the respiration of the turtle? Does it breathe when under water?
5. What sense organs has a turtle? Which appears to be most highly developed? How do you know?
6. In what various ways is the turtle protected against enemies? (You should state several.) Are you afraid of a turtle? If so, why? Why does the turtle need more protection than the snake or lizard?
7. Describe the color pattern of the turtle you are studying. Is this arrangement of colors the same for others of the same species?
8. Describe the arrangement of the epidermal plates of the turtle's shell. Are the arrangement, number, and form of plates the same for all turtles of this species? Compare with the plates of other species. What variations do you find?

Reptiles: A General Review and Library Exercise

1. Characteristics of reptiles.
2. Orders of reptiles. Characteristics and examples of each order.
3. Poisonous snakes found in the United States. The poison fangs of a rattlesnake. Habits of the rattlesnake.
4. Cures for snake bites, fabled and real.
5. Snake charming.
6. Famous poisonous snakes and their habits.
7. The characteristics and habits of alligators.
8. The characteristics and habits of marine turtles. How they differ from pond turtles.
9. For what is each of the following noted? Where does it live? The terrapins? the horned toad? the Gila monster? the chameleon? the glass snake?
10. Reptiles of former (geological) times compared with those of the present.
11. Care of eggs and young. Swallowing of young by snakes.
12. Food of snakes. Defend the proposition that non-poisonous snakes are beneficial and should not be killed wantonly.
13. Investigate and write an account of the economic value of reptiles.

D. Studies of Birds

Vertebrates specialized for Flight

The Living Pigeon

The Body.

1. What divisions of the body are present? Compare the relative size of these divisions with that of other vertebrates studied. Can you account for the great increase in bulk of the trunk over the other divisions? How do you account for the longer neck?

Flight.

1. What is the shape of the body? How is the body made smooth? To what is the shape and smoothness adapted? (Recall the appearance of a plucked pigeon or chicken.)
2. Observe the size of the wings by measuring their width and spread (measured from tip to tip when outspread). Where on the body are they attached? How is this point of attachment advantageous? What is the shape of the upper surface of a wing when spread? of the lower surface? How is this shape advantageous in flight?
3. Where are the largest and strongest feathers? How are they arranged with respect to each other: (a) to prevent air passing through on the down stroke of the wing? (b) to permit folding?
4. What is the shape and width of the tail when outspread? when folded? In what way does the tail assist in flight?

Walking and Perching.

1. Identify the parts of the leg as in the frog. (See study of frog.) With what exoskeletal structures is each part covered? How many toes are there? Does the pigeon walk on its foot or on its toes? Where is the ankle joint?
2. The bird's legs are arranged to support the body. How is this brought about? Compare with the lizard and frog in this respect.
3. Explain how the legs are adapted (a) to preserve the balance of the body, and (b) for perching. Are they well or poorly adapted for locomotion? Explain. For what other purposes are the legs sometimes used?

Feeding and Drinking.

1. What is the form and character of the jaws of the pigeon (called the beak)? Offer food, and watch the pigeons eat. How does a pigeon seize and swallow food? Does it chew the food? Locate the crop. If the pigeon chewed its food, would it have a crop? Why? How does a pigeon drink? How does the chicken drink?

Respiration.

1. What parts move in breathing?
2. Compare roughly the body temperature (by touch) of man, the pigeon, and the frog. Which has the highest temperature? which the lowest? How can you account for the higher temperature of the bird? (Which of the three must be able to endure long-sustained effort? What is the effect on your own body of long-continued effort?)

Sense Organs.

1. Identify the eyes, ears, and nostrils, and describe their location. What are the advantages in having the eardrum at the bottom of a canal? Is there any disadvantage? What is the probable function of the inner thin eyelid? How does it work?
2. Investigate the power of response of the special senses. Which seems to be the most alert? State the experiments which you used and your reasons for your answers to this question. Which senses are most serviceable in finding food? in protecting against enemies?

Protection.

1. In what different ways are feathers protective to the bird? Study the arrangement of the feathers to find how protection is increased in this way. How do the feathers and parts of feathers which lie next the body differ from those which are on the outer surface? What parts of the body are unprotected by feathers? How are these protected, if at all?
2. Note the flexibility of the neck. Through what part of the arc of a circle can the pigeon turn its head? How is this especially important to birds?
3. What means of defense has the pigeon when attacked?

Summary.

1. Make a list of the important adaptations of the pigeon, (a) to flight, (b) to feeding, (c) to perching, and (d) to protection.
2. Which is the most highly specialized, the fish, frog, snake, or bird? Give reasons for your answers.
3. In what various ways are feathers of use to the bird?

Suggested drawings.

1. Side view of the head.
2. A foot.
3. A wing.
4. Side view of the pigeon.

Supplementary Studies of the Pigeon

These topics and questions should be answered from experience with pigeons and observations of their habits and behavior, and from books to be obtained from the school and public libraries.

1. The homing instinct of the common blue pigeon and of carrier pigeons.
2. Nesting habits, number of broods and number of young in each brood, feeding the young. Why is this method of feeding the young necessary?
3. Varieties or breeds of pigeons. How the various varieties were produced; how they are kept true; reversions of type.
4. Darwin's experiments with the pigeons; object of the experiment. Whitman's experiments.

The Exoskeleton of the Bird: Plumage

Observations.

The pupils should study the arrangement of the feathers and their variations in form and size, and should identify the following principal kinds:—

Contour feathers,

those feathers, generally broad, which cover the body, giving to it its outline and color.

Coverts,

those feathers which cover joints, such as the joints of the wing and tail.

Primaries or pinions,

the long stiff feathers of the outside of the wing, used in sustaining the bird in flight.

Secondaries,

the shorter, more symmetrical feathers lying next and over the primaries.

Down,

soft feathers found on young birds and next to the skin on some adults.

Thread feathers,

best seen about the eyes, ears, and beak.

Quill,

the bare stiff portion, one end of which is inserted in the skin. Examine its internal structure.

Vane,

the broad expanded portion, the part ordinarily seen on the bird.

Shaft,

the mid-rib of the vane.

Barbs,

the delicate outgrowths of the shaft making up the vane.

Barbules,

the subdivisions of the barbs, some of which are provided with hooklets. These may well be studied microscopically.

Questions.

1. How is the plumage arranged to offer least resistance to the air in flight? How does a bird sit when exposed to the wind?
2. In a column write the names of the parts of a feather, and opposite each part state its particular use.
3. Of what use are the hooklets on the barbules?
4. State and explain the peculiar position of the shaft of the primary feather; of that of a contour feather.

   The plumage of many birds contains all stages of feather specialization, from down to pinion. Find as many of them as you can on your specimen.

5. What reason can you assign for the fluffy base and the compact end of the contour feather?
6. How much of the feather of a full-grown bird seems to be supplied with blood vessels? How does this bloodless or full-blooded condition affect the weight of the feather; of the plumage; of the bird?
7. How would the above condition affect the temperature of the blood and of the body? Would it tend to cool the animal or to conserve its heat?
8. Show how the air lying motionless amongst the plumage may serve the same purpose as that in the packing of a fireless cooker or a "thermos bottle."
9. How would the above condition affect the growth and repair of the feather? What connection has it with moulting?
10. What kind of feathers forms most birds' "baby clothes"? What kind forms the adults' "underclothes"?

Suggested drawings.

1. A typical feather.
2. A feather of each kind.
3. A bird with wings outspread, showing positions of feathers.
4. The minute structure of a feather.

Birds and Migration

Work in the Laboratory

In describing the colors of birds, great discussions often arise because pupils do not use terms correctly. Consult Chapman's "Birds of Eastern North America" for a color key or chart, and train yourself to observe colors carefully and name them correctly. You will find more colors among birds than are given there, but the chart will help you a great deal.

Study in the laboratory as many birds as you can. Try to get one of each order at least and, among the perching birds, one of each family. The answers to the following questions should be recorded upon the blank outlines of birds, or else in the form of a table.

Questions.

1. How long is the bird?
2. What is the general color of the upper surface; of the lower?
3. What are the markings or peculiarities of the head, if there are any?
4. Note any peculiarities of the tail, as to shape, length, or color, if there are any.
5. If the wings are not like the back, note their color, and, if there are wing bars, note their number and color.
6. What are the markings on the breast, if there are any?
7. Note any other markings, as rump spot, etc.
8. What sort of beak has the bird?
9. What sort of feet has it?
10. Identify the bird, using any key or guide you have. Do not ask any one to help you until you have exhausted your own resources.

Comparative Study of Birds

1. In what ways do the feet of birds vary? Give examples to illustrate your answer. What are the principal results of these variations?
2. In what ways do the beaks of birds vary? Give examples of the variations and of the special uses of the beaks.
3. How do water birds differ from land birds; flesh-eating birds from seed eaters; insect-eating birds from seed eaters; shore and swamp birds from land birds?

Work in the Field

1. Over what length of time have your observations extended? Where have you studied? What have you found to be the best conditions for studying birds? How many birds have you identified?
2. When in the year do birds migrate; when in the twenty-four hours?
3. In spring migration which birds come first; which come last? What reason is there for this order?
4. What may retard migration? What may hasten it?
5. What could prevent certain birds from ever coming here, or, if they did come, from staying?
6. Name some birds which stay here permanently; some which come only for the winter; some which come for the summers; some which merely pass through, going and coming.
7. Can you see anything which may determine whether a bird will nest here or farther north? If so, what is it?
8. Why is the house sparrow so successful?
9. Why are blue jays so nomadic in winter?
10. What months do the herring gulls stay here? When do they leave? Where do they go when they leave? What do they do while they are gone? When do they return? What is their economic value?
11. How many birds' nests have you seen this spring? To what kinds of birds did they belong? If you have been able to study one in particular, give its history as far as you know it.
12. Tell what you have learned by your own observation this spring concerning the kinds of food birds eat, and their methods of obtaining food.
13. What bird songs have you learned to know? When do these birds sing most? Does a bird have more than one song?
14. What birds have you seen near your home? What attached them to the vicinity? How might you attract more birds?

Birds; Review and Library Exercise

1. What are the distinguishing characteristics of birds?
2. Give the orders of birds, with the characteristics of each order and an example of each.
3. Define and give illustrations of the meaning of the expressions: "land birds;" "water birds;" "shore birds;" "swamp birds;" "scavengers;" "policemen of the air."
4. Discuss the temperature of birds, the amount of energy they show, and the oxygen they use.
5. Beaks of birds.
6. Feet of birds.
7. The crop and gizzard. Why absent in many birds?
8. What is there in a bird's construction which enables it to twist its head so far around? What are the advantages in being able to do so?
9. Account for the oiliness of plumage of water birds; for the complete feathering of legs and feet in some forms.
10. Define moulting and discuss its advantages and disadvantages.
11. Give reasons why you would not expect a bird to hibernate.
12. Name two or more kinds of birds which show "recognition marks." What sort of birds would you expect to find with such marks? Why?
13. Is a bird's egg alive when it is laid? Why does it have so much food stored in it? What direct interest have we in this fact?
14. How are the eggs of various birds protected while they are developing?

    Note.—Do not be satisfied with only one way. A bird seldom is.

15. Compare præcocial and altricial birds as to their stage of development when hatched; the location and character of the nest; the care given by the parents; the singing habit of the parents; the success of the type.
16. Name at least three insect-eating birds and tell how many insects it is estimated each will destroy in a day. Effect in a garden?
17. [**check nested paras]If you had an orchard to protect from insects would you spray it with poison, or would you police it with birds?

    Note.—Consider both sides. There is much to be said on each.

    If you decided that you needed more birds, how would you get them?

18. Suppose you had a city lot in the suburbs, 50 feet wide by 200 feet deep, with a house covering the first 50 feet. Make a plan of the back yard to show what you could do to attract the birds to it in the summer; in the winter. Remember that birds must have protection against enemies as well as against changes in weather, etc.
19. For what purposes are birds killed by man? Which of these do you consider legitimate? Which birds may not legally be killed at any time of the year in this state? Which may at certain seasons? Which may at any time? When should an "open season" be permitted? How long should it last?
20. Give a short biography of Audubon. Describe the purpose of the Audubon Society and some of the work accomplished by it.
21. When were the house sparrows, or, as we call them, the English sparrows, introduced into this country? Where? Why? Have they proved a success from our standpoint? From their own? Why have they increased so enormously? What part of the country is still free from them? Why? Give the reasons for and the methods of fighting English sparrows.
22. The history of the passenger pigeon.
23. What has the quail or bobwhite to do with our food supply?
24. Poultry keeping.
25. Name three bird magazines and give a characteristic of each one.
26. Fossil birds and the light they shed on the probable ancestry of birds.

Study of the Migration of Animals in General

1. A map to show the migration route of the birds of your region.
2. A map to show the migration of the potato beetle (or English sparrow or any other animal the extension of whose range has been studied).
3. A map of the world, showing the zonal areas.
4. A map of North America, showing the distribution of the ungulates, with the boundaries and barriers marked.
5. A map of North America, showing the distribution of the fur-bearing animals.
6. A map of the world, showing the distribution of the human races.

E. Studies of Mammals

To illustrate Man's Relation to Other Animals; the Connection between Mode of Life and Structure

The Rabbit

The Body.

1. What divisions of the body are there? Compare the length and use of the neck with that of the pigeon. Describe the character and length of the tail. What use has it, if any?

Locomotion.

1. What methods of locomotion has the rabbit? Which is most commonly used?
2. Study the limbs, and find the ankle and wrist. Does the rabbit walk on its foot or its toes? Note the number and character of the toes and fingers and their claws. What is the effect of the nonretractile power of the claws upon the uses to which claws can be put?
3. What uses have the fore or the hind limbs other than locomotion? Explain how the usual sitting or resting posture is advantageous for quick locomotion.
4. By means of printer's or writing ink smeared over the soles of the feet, and a long piece of clean white paper get prints of a rabbit's tracks as it hops over the paper. Explain how the peculiar formation of the tracks occurs.

Feeding.

1. Offer a rabbit various kinds of food. How does it test the food before eating? Does the rabbit ever use its forelimbs to assist in feeding? If so, when and how? How is the food eaten? How are the teeth fitted for the rabbit's method of feeding? Does your rabbit drink? If so, how?

Respiration.

1. What movements of the body are concerned in breathing?
2. Compare the frequency of the breathing movements with your own. Can you distinguish the heart beats? If so, how and where? Count them.

Sense Organs.

1. Note the position of the eyes, shape of their surface, shape and size of the pupil. What external protecting structures are present,—such as eyelids, eyelashes, eyebrows? Study the movements of the eyelids. Is there a third eyelid as in the bird? Compare the use of the neck in enlarging the range of vision with that of the bird. Is the rabbit's range of vision greater or less than your own?
2. What is the location of the nostrils? What advantages are gained by the prolongation of the face forward? Note any peculiarity in the form or movement of the nostrils. How do you explain these movements? Are the nostrils more or less useful than those of other vertebrates you have studied? How?
3. Note the shape, size, and position of the external ears and explain what relation, if any, these characters of the ears have to hearing. Note the various movements of the ears and the reasons for these movements.
4. What special organs for touch has the rabbit? Under what circumstances are these of use? What parts of the body are most sensitive to touch?

Protection.

1. What home-making habits do you observe in the rabbit? What habits relating to secrecy, comfort, and safety, do you observe?
2. Study the fur and hair of the rabbit. How do you distinguish between fur and hair? What variations do you find in the fur and hair? What parts of the body are uncovered? Why? What are the various functions of the fur and hair covering of rabbit?
3. Have rabbits any means of defense or offense? Explain.

Social Habits.

1. Notice and describe anything in the behavior of the rabbits which may be classed as social,—such as play, fondness for company, display of affection, homing instincts, care of young, etc.

Supplementary Study of Wild Rabbits

1. What method of locomotion is more highly developed in wild rabbits than in domestic rabbits? Why?
2. When do wild rabbits do their feeding? Why? In what ways do they sometimes do damage in feeding?
3. What senses will probably be more alert than those of the domestic rabbit? Why?
4. Where do wild rabbits usually make their homes? Why? How do they guard against being cornered in their homes?
5. In what ways do they guard against surprise when feeding? What are the principal enemies of rabbits? What devices do they employ to escape enemies when pursued by them? What is thumping? When used?
6. How many young rabbits are usually produced at one time? How many litters in a season? How long does it take a young rabbit to mature?
7. How are the young of rabbits guarded against danger from enemies and weather? What are the various causes that tend to keep down the numbers of rabbits?
8. Give an account of the plagues of rabbits in Colorado and Australia, including the reasons for the great increase in numbers and the methods used to destroy the rabbits.

Summary of the Study of Rabbits

1. What has been the general effect of domestication upon rabbits?
2. What are the most important characters and habits that fit the wild rabbit for its life?

The Guinea Pig or White Rat

1. What regions of the body can you identify? What is the relative length of the neck, ears, legs? What about the tail?
2. Describe the color scheme of the animal. Is it protective or the result of breeding? What is the character of the covering?
3. Describe the method and rate of locomotion. Would this method of locomotion enable the animal to escape from enemies (e.g. dogs)?
4. What is the shape of the foot? What is the shape and length of the claws? For what are they adapted?
5. What sounds do the animals make?
6. What is the appearance and shape of the eye? What is the color of the eye?
7. State the size and shape of the external ear. What movements are characteristic?
8. What motions of the nostrils do you see?
9. Feed the animal various kinds of food. How does it eat? State any facts you observed, to show that it has or has not a choice as to food.
10. Watch the animal for some time to determine its mental characteristics. Is it alert? curious? timid? Does it show much intelligence? affection?

What is the relation between mental development and success in the struggle for existence?

Summary.

1. What are the general characteristics of the animal?
2. To what kind of life is it adapted?
3. What are some of the characteristics that make the animal a good pet?

The Squirrel

Before taking up the study of the squirrel in the laboratory a trip should be made to some park or wooded region and the habits of squirrels noted. Take your camera and try to take some snapshots. After the laboratory exercise visit some museum or zoölogical garden and study the relatives of the squirrel.

Observations based upon field work.

1. What different postures does the squirrel assume?
2. What does it do when frightened?
3. What use have the forelegs other than locomotion?
4. How does a squirrel go up a tree? down? from branch to branch? State all the forms of locomotion you have noticed.
5. What is the appearance of the tail? What is the position of the tail when the squirrel is sitting? running? on a branch? Describe any motions of the tail you noticed. Is there anything expressed by these motions or are they without meaning?
6. Tempt the squirrel with some nuts. State the evidence that leads you to think that the squirrel is alert, timid, curious. Do you think the squirrel acts most from instinct or as the result of intelligence?
7. In what various ways does a squirrel attempt to escape notice? What does it do when you chase it?

Observations in the laboratory.

1. What divisions are there to the body? What is the length of the neck? the length and appearance of the tail?
2. What is the relative length of the legs as compared with the body? How does the length of the front and hind legs compare?
3. Does the animal walk on its toes or on the sole of its foot? How many toes on each foot? What is the length of the claws? For what could they be used?
4. Offer the squirrel various kinds of food and see if it has a choice. Describe its methods of eating.
5. Note the position of the eyes, the shape of their surface, and the shape and size of the pupil. How many eyelids do you notice? Why do the squirrel's eyes appear so "bright"? Are eyebrows, eyelashes, or tear glands present?
6. Note the size, shape, and appearance of the squirrel's external ears.
7. What movements of the nostrils do you notice? For what does a squirrel chiefly use his nostrils? What explanation can you suggest for the nostrils, eyes, and ears having the same relative position in all vertebrates?
8. How does a squirrel protect itself?
9. Smear the feet of a squirrel with ink and allow it to run over a roll of clean paper as in the case of the rabbit. How do its tracks differ from those of the rabbit?

Summary.

1. What are the general characteristics of the squirrel?
2. To what kind of life is it adapted?
3. What adaptations has the squirrel to protect it from its enemies?
4. What characteristics make the squirrel a good pet? What objections to it?

Library Exercise on Rodents

1. General characteristics and examples of rodents. The teeth of rodents.
2. Show how variation in habitat depends upon structure among rodents by comparing, for example, squirrels, beavers, and woodchucks.
3. Variations in the tails of rodents. What are the causes of this variation?
4. Pocket gophers and their economic relations.
5. Species of mice. Their habits.
6. The dancing mouse.
7. Damage by mice. Plagues of field mice in Nevada. Method of extermination.
8. Habits and kinds of rats.
9. Economic importance of rats. Methods of extermination.
10. Rats and the bubonic plague.
11. Squirrels, kinds and habits.
12. The economic value of rabbits.
13. The groundhog myth. Habits of woodchucks.
14. The beaver—their habits and sagacity. Methods of trapping them.
15. Prairie dogs—their habits and economic importance. How exterminated?
16. What are porcupines?
17. Variation in the homes among rodents. Usual means of defense.
18. Make a list of rodents in a column, and in another column opposite each name write the various ways the animal is of economic importance. Sum up with a statement showing the most important ways rodents are of value to man and harmful to man.
19. Defend the proposition that rodents are on the whole harmful animals and should be exterminated.
20. How some rodents contribute to the science of medicine, more especially to bacteriology.

The Cat or Dog—Carnivora

Living specimens of cats or dogs. Pictures, books, lantern slides, etc. Supplement the laboratory study with trips to museums and zoölogical gardens to observe the relatives of the cat.

Definitions.

Carnivora.

An order of mammals, chiefly flesh-eating, with claws and well-developed canine teeth.

Carnivorous,

flesh-eating.

Herbivorous,

plant-eating.

Omnivorous,

eating both plants and animal food.

Digitigrade,

walking on the toes.

Plantigrade,

walking on the soles of the feet.

Vibrissæ,

long hairs on the face—"whiskers."

Observations.

1. Into what regions is the body divided?
2. What is the shape of the head and the length of the neck?
3. Are the legs relatively long or short? How do the front and hind legs compare in length? How many toes on each foot? Is the cat digitigrade or plantigrade?
4. How many pads on the sole of the foot? What use can you suggest for these structures? What is the size and shape of the claws? Are they retractile or nonretractile? For what purposes may the claws be used?
5. Describe the tail as to length and appearance. Movements.
6. What is the size and appearance of the external ears? What movement do you notice?
7. Are the eyes large or small? What eyelids can you find? What other accessory structures? What is the shape and direction of the pupil?
8. What other sensory structures do you find? What is their function?
9. Watch the animal eat. Does it chew or "fletcherize" its food? What teeth seem well developed? Is the movement of the jaws simply up and down, or is there a lateral movement as well?
10. Try to find out some of the mental characteristics of the animal, i.e. is it sluggish or active? Is it alert? Does it show curiosity? fear? What evidence of intelligence?

Supplementary studies.

1. Smear the feet of a cat with ink and allow it to run on a sheet of clean paper. Make a diagram to show tracks. Do the same in case of a dog. How do these tracks differ? Why?
2. What is the difference between a cat and a dog as to the manner of eating a bone?
3. As you see dogs and cats outside do you see any evidence in either case of a tendency to gather in packs (gregariousness)?
4. What different emotions are expressed by a dog's tail? a cat's tail?
5. What sounds do cats and dogs make? Significance?
6. Contrast the sleeping habits of cats and dogs.
7. How large is the litter in case of dogs and cats? Condition of young at birth? How long before the eyes of the young are open? Care of young.

Summary.

To what kind of life does a cat or dog seem best adapted: (a) as to food? (b) protection from enemies?

Carnivora; Review and Library Exercise

Morphology and physiology.

1. The dentition of the cat, the dog, and the bear. Variation in the "chewing teeth."
2. Three types of paired appendages among carnivora. Relation to habitat.
3. The difference in structure and use of the posterior legs of the seal and walrus.
4. The alimentary canal of a cat and rabbit compared.
5. The tongue of cats and dogs contrasted as to structure and use.

Economics.

1. The difference between hair and fur.
2. The fur-bearing carnivora. Families, and habitat.
3. Trapping.
4. Game laws and game wardens. Hunters' licenses.
5. Hunting big game.
6. Carnivora harmful to man.
7. Carnivora useful to man.
8. Carnivora as pets.
9. Chief types or breeds of domesticated dogs. Characteristics. Special value of each.
10. Chief types or breeds of domesticated cats.
11. Dogs as burden bearers.

Natural History.

1. Distribution and range of carnivora. Carnivora of the United States.
2. Winter habits among carnivora.
3. Food of carnivora. Various methods of obtaining it.
4. The hunting habits of the dog and cat family.
5. The habits and distribution of the raccoons.
6. The color schemes of the more important families of the carnivora.
7. Seasonal variation in color.
8. Distribution and habits of the ferrets and weasels.
9. How carnivora protect themselves from enemies. Which carnivora have been most successful in resisting man's advance?
10. Peculiar and interesting carnivora to be seen in museums and zoölogical gardens.
11. Origin of the domestic dog.
12. Intelligence of dogs.
13. Fox-hunting.
14. Coyotes and their relation to stock raising, etc.

The Ungulates