A Text-book of Entomology / Including the Anatomy, Physiology, Embryology and Metamorphoses of Insects for Use in Agricultural and Technical Schools and Colleges as Well as by the Working Entomologist

3. Comprising ovaries whose ends above the egg-germs contain a well-developed mass of cells functioning as a yolk-forming organ, between whose special elements grow root-like offshoots of nearly ripe egg-cells. (Hemiptera.)

When the egg is ripe the food-chamber disappears because its contents have served for the formation of the egg below it. In Lepidoptera especially, the egg-tubes resemble strings of pearls because most of the numerous eggs ripen simultaneously and are likewise deposited at the same period, which is naturally not the case in those insects whose eggs gradually ripen (Fig. 477). In other cases the egg- or food-compartments are transformed into each other, but only one egg- and one food-compartment can be situated in the same dilatation of the ovarian tube. Finally, there are insects in whose egg-tubes the egg-compartments are arranged in a single row, while the capacious terminal chamber contains a large mass of food-cells.

Egg-cells, nutritive cells, as well as the cells of the follicle epithelium (epithelium of the chambers of the ovarian tubes), originate as similar or homologous elements, division of labor leading to their later differentiation. Only a few of the numerous egg-germs develop into eggs, the rest serving as envelopes and also as food for these few. (Lang.)

In many insects the egg-tubes open into an egg-calyx (Fig. 478, c), in which the ripe eggs collect before passing into the oviduct (ov).

As the result of his investigations on the origin of the cellular elements of the ovaries of insects Korschelt concludes:—

1. The different cell-elements of the egg-tubes, eggs, nutritive cells, and epithelium arise from identical undifferentiated elements situated in the contents of the earliest germ of the egg-tubes.

2. The first formation of the cellular elements present, and the differentiation of the individual compartments of the egg-tube, occur during embryonic and larval life.

3. The undifferentiated elements of the terminal chamber correspond to the embryonic condition, while in post-embryonic time, and even during imaginal life, a new formation of the different kinds of cells takes place.

4. The mode of origin of the different kinds of cells from the undifferentiated elements varies greatly in different insects.

5. From their histological nature, and from the mode of origin of their elements, the most complex egg-tubes and those provided with nutritive compartments are phylogenetically derived from those without such nutritive compartments.

6. The nutritive cells in certain cases originate in the same way and at the same time as the germ-cells, and are therefore to be regarded as germ-cells which have abandoned the function of egg-making, and exchanged it for the production of nutritive material.

7. In the egg-tubes with numerous nutritive compartments the nutritive cells can originate at the same place as the egg-cells, and they afterwards still lie intermingled with these in the beginning or upper part of the egg-tubes.

8. While the capability of egg-making of the germ-cells originally situated in the extremity of the terminal chamber gradually becomes transferred to those at the base of the terminal chamber, and the first transform into nutritive cells, egg-tubes with nutritive compartments at the base may be found.

9. The nutritive cells of certain forms arise independently of the germ-cells and therefore could not have previously originated from them.

10. The epithelium has in all forms nearly the same mode of formation; it everywhere shows a close similarity to the undifferentiated elements of the terminal chamber, out of which it directly develops. As to the fact of formation of epithelium through the germ-vesicles (Keimblaschen), nutritive-cell nuclei, or the so-called “oöblasts,” I could not feel certain.

11. Neither the eggs of Hemiptera or of other insects arise through the agency of “oöblasts,” but like the epithelial and nutritive cells arise by a gradual differentiation from the indifferent elements of the ovarian tubes.

12. The different elements of the egg-tubes, also the eggs, have the morphological value of cells.

Origin of incipient eggs in the germ of the testes.—Heymons has detected in the germ of the testes of the male larvæ of Phyllodromia germanica 7 mm. in length, young or incipient eggs, similar to those seen in the ovarian tubes of the female larva of the same size. In another male larva of the same size also occurred short cylindrical tubes each with a terminal thread, which had the appearance of rudimentary egg-tubes. Hence he thinks that every part of the genital germs (Anlagen) in the male, which are not concerned in the formation of testicular follicles, represents the germ of a female genital gland. As is well known, no insects are hermaphroditic, but this case of the practical origin of eggs and egg-tubes in the lowest division of the male efferent passage, which is homologous with the egg-producing division of the female ovarian tubes, points back to hermaphroditic ancestors. And Heymons suggests that the frequent occurrence of hermaphroditism in insects probably confirms this view.

The bursa copulatrix.—The copulatory pouch in most insects is a special cup-shaped appendage of the vagina adapted for the reception of the male organ during sexual union. Its mode of formation in the cockroach is thus described by Haase:—

“By the retreat of the female sexual aperture, situated in the 8th ventral plate, a considerable space, the genital pouch, is produced; this is formed chiefly by the extended connective membrane between the elongated 7th and 8th ventral plates. This serves for the development of the egg-cocoon, which is retained by the internal appendages of the posterior gonapophyses.”

The fertilization of the female takes place once for all a long time previous to oviposition; the semen in the receptaculum seminis passes out as the eggs slip down the egg-passage, and a spermatozoön gains entrance into the interior of the egg through the micropyle. In Œcanthus, according to Ayers, fecundation probably takes place while the egg is passing into the vagina, “since it is hardly possible that the male element could gain access to the follicles before the chorion is secreted.”

In the Lepidoptera, as has been stated, the copulatory pouch opens separately from the opening of the oviduct (vagina), but a slender canal connects the pouch with the vagina (Fig. 310, bc). The outlet (“vagina” of Burgess) of the copulatory pouch opens between the 7th and 8th segments, that of the oviduct (vagina) on the 9th segment being “situated immediately below the anus and hardly separated from it, between the lappets of the 9th segment.” (Burgess.) The opening of the copulatory pouch is, as we have seen, the genuine or primitive sexual opening.

The spermatheca.—This is a sac or pouch for the reception and storage or preservation of the semen. While in most of the higher insects it opens into the dorsal wall of the vagina (Fig. 472, f), in the cockroach, locusts, and grasshoppers it opens into the bursa; but in other European Orthoptera, as in most insects, it lies upon the dorsal wall of the vagina. (Berlese.) In the cockroach, it is a short tube dilated at the end and wound into a spiral of about one turn. “From the tube a cœcal process is given off, which may correspond with the accessory gland attached to the duct of the spermatheca in many insects (e.g. Coleoptera, Hymenoptera, and some Lepidoptera). The spermatheca is filled during copulation, and is always found to contain spermatozoa in the fertile female. The spermatozoa are no doubt passed into the genital pouch from time to time, and there fertilize the eggs descending from the ovarian tubes.” In Meloë the spermatheca is exceedingly large. (Miall and Denny, pp. 170, 171.)

The colleterial glands.—We have already briefly referred to these glands. Those of the cockroaches form a number of long blind tubes opening into the vagina. They furnish the material for the egg-capsule or oötheca, viz. chitin and large crystals of oxalate of lime.

In Phyllodromia germanica “these glands are glistening white till the time of oviposition approaches, when they assume a yellow tint, and the octahedral crystals are seen imbedded in a viscid substance which fills their lumina. This viscid substance is soluble in potassium hydrate, and is consequently not chitin. When excreted to form the oötheca, it slowly hardens, deepens in color, and becomes insoluble in potassium hydrate. Light has nothing to do with this change, which is possibly produced by the oxygen in the air. It is the same change which is undergone by the cuticula of the insect itself immediately after ecdysis.” (Wheeler.)

The vagina or uterus.—This is simply the end of the common oviduct, which, when dilated, is called the vagina, and, in the pupiparous forms, the uterus.

In the cockroach the vagina opens by a median vertical slit situated in the 8th sternite, into the genital pouch or bursa, upon the dorsal wall of which the orifice of the spermatheca is situated. In the sheep-tick the oviduct is enlarged to form the so-called uterus, which furnishes a milk-like secretion for the nourishment of the larva during its intra-uterine life.

In insects in general, the external opening of the vagina is simple, the chitinous structures (valves) at the opening being adapted to receive the male intromittent organ.

When the eggs are to be deposited deep below the surface of the earth, or in wood, or in wood-boring larvæ, or in the body of caterpillars, etc., they are inserted by the ovipositor (see p. 167).

Signs of copulation in insects.—Leydig has collected, partly from his own observations and partly from those of others, a number of cases in which female insects bear traces of having had sexual union, in the form of tags or plates attached to the body, and apparently formed from material secreted by the male. Such probably is the “pouch” on the abdomen of Parnassius apollo, and a somewhat similar structure in Fulgora laternaria, and such is the plate which is found on the hinder part of the abdomen of Dyticus latissimus and D. marginalis. Leydig compares these structures with the white plate in Astacus fluviatilis, and with the little white lid on the spider Argenna, and finds analogues among vertebrates. (Arbeit. Zool. Zoot. Inst. Wurzburg, x, 1891, pp. 37–55, 2 Figs.)

LITERATURE ON THE ORGANS OF REPRODUCTION

a. General

Hunter, J. Observations of bees. (Phil. Trans. Roy. Soc. London, 1792, lxxxii, pp. 128–195.)

Hegetschweiler, J. J. Dissertatio inauguralis zootomica de insectorum genitalibus. Turici, 1820, pp. 28, 1 Pl.

Audouin, V. Recherches anatomiques sur la femelle du Drile jaunatre et sur le male de cette espèce. (Ann. Sc. nat., ii, 1824, pp. 443–462, 1 Pl.)

Müller, Johannes. Ueber die Entwickelung der Eier im Eierstock bei den Gespenstheuschrecken. (Nova Acta Acad. Leop.-Carol., xii, 1825, pp. 555–672, 6 Taf.)

Dufour, L. Recherches anatomiques sur les Carabiques et sur plusieurs autres insectes coléoptères. Organes de la génération (Ann. Sc. nat., vi, 1825, pp. 150–206, 6 Pls.; pp. 427–468, 4 Pls.).

—— Recherches anatomiques sur l’Hippobosque des cheveaux. (Ibid., 1825, vi, pp. 299–322, 1 Pl.)

—— Recherches anatomiques sur les Labidoures. Appareil de la génération. (Ibid., 1828, xiii, pp. 354–359, 2 Pls.)

—— Recherches anatomiques et considérations entomologiques sur quelques insectes coléoptères, compris dans les familles des Dermestins, des Byrrhiens, des Acanthopodes et des Leptodactyles. Appareil génital. (Ibid., Sér. 2, Zool. i, 1834, pp. 76–82, 2 Pls.)

—— Résumé des recherches anatomiques et physiologiques sur les Hémiptères. (Ibid., Sér. 2, i, pp. 232–239.)

—— Mémoire sur les métamorphoses et l’anatomie de la Pyrochroa coccinea. Appareil génital. (Ibid., Sér. 2, Zool., xiii, pp. 337–339, 1 Pl.)

—— Histoire des métamorphoses et de l’anatomie des Mordelles. (Ibid., Sér. 2, xiv, pp. 235–238, 1 Pl.)

—— Anatomie générale des Diptères. Appareil génital. (Ibid., Sér. 3, Zool., i, 1844, pp. 250–264.)

—— Histoire des métamorphoses et de l’anatomie du Piophila petasionis. Appareil génital. (Ibid., Sér. 3, Zool., i, 1844, pp. 378–386.)

—— Études anatomiques et physiologiques sur les insectes diptères de la famille des Pupipares. Appareil génital. (Ann. Sc. nat., Sér. 3, Zool., iii, 1845, pp. 73–93, 2 Pls.)

—— Recherches sur l’anatomie et l’histoire naturelle de l’Osmylus maculatus. Appareil génital. (Ibid., Sér. 3, Zool., ix, 1848, pp. 349–356, 1 Pl.)

—— Recherches anatomiques sur les Hyménoptères de la famille des Urocerates. Appareil génital. (Ibid., Sér. 4, Zool., i, 1854, pp. 216–234, 1 Pl.)

—— Fragments d’anatomie entomologique. Sur les ovaires du Nemoptera lusitanica. (Ibid., Sér. 4, viii, 1857, pp. 9–10, 1 Pl.)

—— Fragments anatomiques sur quelques Élatérides. (Ibid., Sér. 4, viii, 1857, pp. 365–372, 1 Pl.)

—— Recherches anatomiques et considérations entomologiques sur les Hémiptères du genre Leptopus. Appareil génital. (Ibid., Sér. 10, 1858, pp. 356–362, 1 Pl.)

—— Recherches anatomiques sur l’Ascalaphus meridionalis. Appareil génital. (Ibid., Sér. 4, xiii, 1860, pp. 203–206, 1 Pl.)

—— Sur l’appareil génital male du Coræbus bifasciatus. (Thomson’s Archiv Ent., 1857, i, pp. 378–381.)

Suckow, F. W. L. Geschlechtsorgane der Insekten. (Heusinger’s Zeitschr. f. organ. Physik., 1828, ii, pp. 231–264, 1 Taf.)

Rathke, M. H. Miscellanea anatomico-physiologica. Fasc. 1. De Libellarum partibus genitalibus. Regiomonti, 1832, p. 38, 3 Pls.

Dutrochet, R. J. H. Observations sur les organes de la génération chez les pucerons. (Ann. Sc. nat., 1833, xxx, pp. 204–209.)

Doyère, L. Observations anatomiques sur les organes de la génération chez la Cigale femelle. (Ann. Sc. nat., 1837, vii, pp. 200–206, Fig.)

Siebold, C. Th. E. von. Ueber die weiblichen Geschlechtsorgane der Tachinen. (Wiegmann’s Archiv f. Naturgesch., 1838, iv, pp. 191–201.)

—— Ueber die inneren Geschlechtswerkzeuge der viviparen und oviparen Blattläuse. (Froriep’s Notizen, 1839, xii, pp. 305–308.)

—— Ueber das Receptaculum seminis der Hymenopteren-Weibchen. (Germar’s Zeitschr. f. Ent., 1843, iv, pp. 362–388, 1 Taf.)

Loew, H. Beitrag zur anatomischen Kenntniss der inneren Geschlechtsteile der zweiflügligen Insekten. (Germar’s Zeitschr. f. Ent., 1841, iii, pp. 386–406, 1 Taf.)

—— Horæ anatomicæ, Abth. I. Entomotomien. Heft i-iii, Posen, 1841.

—— Beiträge zur Kenntniss d. inneren Geschlechtstheile der zweifl. Insecten. (Germar’s Zeitschr. f. Entomologie, iii, 1841, pp. 386–406, 1 Taf.)

Stein, F. Vergleichende Anatomie und Physiologie der Insekten. I, Monographie. Ueber die Geschlechtsorgane und den Bau des Hinterleibes bei den weiblichen Käfern, Berlin, 1847, i, pp. 139, 9 Taf.

Brauer, F. Beitrag zur Kenntniss des inneren Baues und der Verwandlung der Neuropteren. (Verhandl. d. zool. botan., Vereins in Wien, 1855, pp. 1–26, 5 Taf.)

Haliday, A. H. Note on a peculiar form of the ovaries observed in a hymenopterous insect, constituting a new genus and species of the family Diapriadæ. (Nat. Hist. Review, 1857, iv, pp. 166–174, 1 Pl.)

Laboulbène, A. Recherches sur les appareil de la digestion et de la reproduction du Buprestis manca. (Thomson’s Archiv Ent., 1857, i, pp. 204–236, 2 Pls.)

Lubbock, John. On the ova and pseudova of insects. (Phil. Trans. Roy. Soc., London, cxlix, 1860, pp. 341–369.)

Landois, H. Ueber die Verbindung der Hoden mit dem Rückengefäss bei den Insekten. (Zeitschr. f. wissens. Zool., xiii, 1863, pp. 316–318, 1 Taf.)

Leydig, F. Der Eierstock und die Samentasche der Insekten. (Nova Acta Acad. Leop.-Carol., xxxiii, 1867, pp. 88, 5 Taf.)

—— Beiträge zur Kenntniss des thierischen Eies im unbefruchteten Zustande. (Spengel’s Zool. Jahrbücher, 1889. Abth. f. Anat., iii, pp. 287–432, 7 Taf.)

Bessels, E. Studien über die Entwicklung der sexual Drüsen bei den Lepidopteren. (Zeitschr. wissens. Zool., xvii, 1867, pp. 545–563.)

Rajewsky. Ueber die Geschlechtsorgane von Blatta orientalis, etc. (Nachr. d. k. Gesellschaft d. Moskauer Universität, xvi, 1875. Testes of cockroach. In Russian; for abstract, see Hoffmann u. Schwalbe, Jahresbericht, 1875, p. 425.)

Brehm, Siegfr. Comparative structure of the reproductive organs in Blatta germanica and Periplaneta orientalis. (Horæ Ent. Soc. Rossicæ, St. Petersburg, viii, 1880.) (In Russian, male organs only.)

Cholodkowsky, N. A. Ueber die Hoden der Schmetterlinge. (Zool. Anzeiger, iii Jahrg., 1880, pp. 115–117.)

—— Ueber den Bau der Testikel bei Schmetterlingen. (Zool. Anzeiger, 1880, iii, pp. 214–215.)

—— Ueber die Hoden der Lepidopteren. (Zool. Anzeiger, 1884, pp. 564–568.)

—— Ueber den Geschlechtsapparat von Nematois metallicus. (Zeitschr. f. wissens. Zool., xliii, pp. 559–568, 1885.)

Tichomirow, A. Ueber den Bau der Sexualdrüsen und die Entwickelung der Sexualprodukte bei Bombyx mori. (Zool. Anzeiger, iii, 1880, pp. 235–237.)

Nusbaum, F. Zur Entwicklungsgeschichte der Ausführungsgange der Sexualdrüsen bei den Insekten. (Zool. Anzeiger, v, 1882, pp. 637–643.)

——On the developmental history of the efferent passages of the sexual glands in insects. Lemberg, 1884 (in Czech).

Berlese, Ant. Ricerde sugli organi genitali degli ortotteri. (Atti della R. Acad. dei Lincei. Ser 3, xi, 1882.) (Genital organs of European Orthoptera.)

Balbiani, G. Le Phylloxera du chêne et le Phylloxera de la vigne. Paris, 1884, pp. 45, 11 Pls.

—— Contribution à l’étude de la formation des organes sexuel chez les insectes. (Recueil Zool. Suisse, 1885.)

Schneider, Anton. Die Entwicklung der Geschlechtsorgane bei den Insekten. Zool. Beiträge, Breslau, i, 1885.

Beauregard, H. Recherches sur les insectes vésicants. Suite. (Journal Anat. Phys., Paris, 1887, xxii Année, pp. 528–548, 1 Pl.; xxiii Année, pp. 124–163, 6 Pls.)

—— Les insectes vésicants. Paris, 1890. Chap. v, Appareil de la génération, pp. 103–159, Pls. 10–12.

Nassonow, N. Études morphologiques sur les Lepisma, Campodea et Podura. (Mém. Soc. Imp. Anthropologie et d’Ethn. Moscou, iii, 1887, pp. 85, 2 Pls., 68 Figs.)

—— Xenos rossii; seine Anatomie und Entwicklungsgeschichte. (Bull. de l’Université de Varsovie, 1892, pp. 74, 2 Taf.) (In Russian.)

—— Position des Strepsiptères dans le systeme selon les données du développement post-embryonal et de l’anatomie, p. 11, Warsaw, 1892.

Grassi, B. J. Progenitori dei Miriapodi e degli Insetti. Memoria vii, Anatomia comparata dei Tisanuri. (Atti d. R. Acad. de’ Lincei, Cl. scienc. e fis., Serie 4, iv, 1888, pp. 435–606, 5 Pls.)

Heymons, R. Ueber die hermaphroditsche Anlage der Sexualdrüsen beim Mannchen von Phyllodromia germanica. (Zool. Anzeiger, 1890, pp. 451–457.)

Koschewnikoff, G. Zur Anatomie der männlichen Geschlechtsorgane der Honigbiene. (Zool. Anzeiger, xiv, 1891, pp. 393–396.)

Verhoeff, C. (See p. 186.)

Ingenitzky, J. Zur Kenntniss der Begattungsorgane der Libelluliden. (Zool. Anzeiger, 1893, xvi Jahrg., pp. 405–407, 2 Figs.)

—— On the fauna and organization of dragon-flies of Russian Poland, 1893, 1 Pl. (In Russian.)

Escherich, K. Anatomische Studien über das männliche Genitalsystem der Coleopteren. (Zeitschr. f. wissens. Zool., lvii, pp. 620–641, 1894.)

Kluge, Max H. E. Das männliche Geschlechtsorgan von Vespa germanica. Inaug. Diss. Leipzig, 1895, pp. 1–45, 1 Taf.

Verson, E. La borsa copulatrice nei Lepidotteri (Atti e Mem. Accad. Sc. Lett. ed Arti, Padova, 1896, xii, pp. 369–372, 4 Pls.).

Klapálek, Fr. Über die Geschlechtstheile der Plecopteren, mit besonderer Rücksicht auf die Morphologie der Genitalanhänge. (Sitzungsb. k. Akad. Wissens. Wien. Math.-Naturw. Cl., cv, 1896, pp. 56, 5 Taf.)

Fenard, A. Recherches sur les organes complémentaires internes de l’appareil génital des Orthoptères. (Bull. Sc. France Belg., xxix, 1897, pp. 390–527, 528–533, 5 Pls.)

Consult also the Works of Ayres, Balfour, Burgess, Burmeister, Bütschli, Claus, Dzierzon, Gensch, Henking, Honert, Huxley, Kluge, Kramer, Landois, Leuckart (art. Zeugung), Leydig, Ludwig, Metschnikoff, H. Meyer, Minot, Müller, Pfitzner, Schneider, Seeliger, Scholz, Siebold, Suckow, Swammerdam, Tichomiroff, Wagner, Waldeyer, Weismann, Wheeler, v. Wielowiejski, Will, Witlaczil, and Ziegler.

b. Formation of the egg (oögenesis)

Claus, C. Beobachtungen über die Bildung des Insekteneies. (Zeitschr. wissens. Zool., xiv, 1864, pp. 42–54.)

Brandt, A. Ueber die Eiröhren der Blatta orientalis. (Mém. Acad. Imp. Scienc. de St. Petersbourg, Sér. 7, xxi, 1874, p. 30.)

—— Vergleichende Untersuchungen über die Eiröhren und die Eier der Insekten. (Nachr. d. Gesellsch. Freunde d. naturwiss. Moskau, xxiii, 1876; also xxiv, 1877, pp. 77–79.)

—— Das Ei und seine Bildungsstatte. Ein vergleichenden-morphologischer Versuch mit Zugrundelegung der Insecteneies. Leipzig, 1878.

Kadyi, H. Beiträge zur Vorgänge beim Eierlegen der Blatta orientalis. Vorläufige Mittheilung. (Zool. Anzeiger, 1879, pp. 632–636.) (Formation of the egg-capsules of cockroach.)

Brass, Arn. Das Ovarium und der Eibildung und der ersten Entwicklungsstadien bei viviparen Aphiden. Halle, 1883. (Zeits. f. Naturwiss. in Halle, Jahrg. 1882.)

—— Zur Kenntniss der männlichen Geschlechtsorgane der Dipteren. (Zool. Anzeiger, 1892, pp. 178–180.)

Will, Ludvig. Zur Bildung der Eies und des Blastoderms bei den viviparen Aphiden. (Arbeiten Zool. Inst. Univ. Würzburg, vi, 1882, pp. 217–258.)

Korschelt, E. Zur Frage nach dem Ursprung der verschiedenen Zellenelemente der Insectenovarien. (Zool. Anzeiger, 1885, pp. 581–586, 599–605.)

Wielowiejski, H. V. Zur Morphologie des Insektenovariums. (Zool. Anzeiger, 1886, ix Jahrgang, pp. 132–139.)

—— Zur Kenntniss der Eibildung bei der Feuerwanze (Pyrrhocoris apterus). (Zool. Anzeiger, 1885, pp. 369–375.)

Blochmann, F. Ueber die Richtungskörper bei Insekteneiern. (Morph. Jahrb., 1887, xii, ix 544.)

Also the writings of Leydig (p. 509).

c. On the spermatozoa

Treviranus, G. R. Ueber die organischen Körper des tierischen Samens und deren Analogie mit dem Pollen der Pflanzen. (Zeitschr. f. d. Physiologie, von F. Tiedemann, G. R. und L. C. Treviranus, 1835, v, pp. 136–153, 2 Taf.)

Siebold, C. Th. E. von. Ueber die Spermatozoen der Crustaceen, Insekten, Gasteropoden und einiger anderer wirbellosen Tiere. (Müller’s Archiv f. Anatomie, 1836, pp. 13–52, 2 Taf.)

—— Fernere Beobachtungen über die Spermatozoen der wirbellosen Tiere. (Ibid., 1836, p. 232; 1837, pp. 381–432, 1 Taf.)

—— Ueber die Spermatozoen der wirbellosen Tiere, iv. (Ibid. 1837, pp. 392–433.)

—— Lange Lebensdauer der Spermatozoen bei Vespa rufa. (Wiegmann’s Archiv f. Naturgesch., 1839, v, pp. 107, 108.)

—— Ueber die Spermatozoiden der Locustinen. (Nova Acta Acad. Leop.-Carol., 1845, xxi, pp. 249–274, 1 Pl.)

Kölliker, A. Beiträge zur Kenntnis der Geschlechtsverhältnisse und der Samenflüssigkeit wirbelloser Tiere, nebst einem Versuch über das Wesen und die Bedeutung der sogenannten Samentiere, Berlin, 1841, pp. 88, 3 Taf.

—— Die Bildung der Samenfaden in Bläschen als allgemeines Bildungsgesetz. (Neue Denkschr. d. allg. Schweiz. Ges., viii, 1847, pp. 28, 3 Taf.)

—— Physiologische Studien über die Samenflüssigkeit. (Zeitschr. f. wissens. Zool., vii, 1856, pp. 201–272, 1 Taf.)

Yersin, A. Observations sur le Gryllus campestris. (Bull. Soc. Vaudoise sc. nat., 1853, iii, pp. 128.)

Lespès, Ch. Mémoire sur les spermatophores des grillons. (Ann. Sc. nat., Sér. 4, iii, 1855, pp. 366–377, 1 Pl.; iv, pp. 244–249, 1 Pl.)

Landois, H. Entwicklung der büschelförmigen Spermatozoiden bei den Lepidopteren. (Schultze’s Archiv f. Anat. u. Physiol., 1866, pp. 50–58, 1 Taf.)

Bütschli, O. Vorlaufige Mitteilungen über Bau und Entwicklung der Samenfaden bei Insekten und Crustaceen. (Zeitschr. f. wissens. Zool., xxi, 1871, pp. 402–415.)

Bütschli, O. Nähere Mitteilungen über die Entwicklung und den Bau der Samenfaden der Insekten. (Ibid., xxi, 1871, pp. 526–534, 2 Taf.)

La Vallette St. George, A. V. Ueber die Genese der Samenkörper, III. Mitteilung. (Archiv f. Mikroscop. Anat., 1874, x, pp. 495–504, 1 Taf.)

—— Spermatologische Beitrage: II. Mitteilung (Ibid., 1886, xxvii, pp. 1–122 Taf.). IV. Mitteilung (Ibid., 1886, xxviii, pp. 1–13, 4 Taf.) V. Mitteilung (Ibid., 1887, xxx, pp. 426–434, 1 Taf.)

Schneider, A. Das Ei und seine Befruchtung, pp. 88, 10 Taf.; Arthropoden, pp. 57–68 und 79. Taf. 8–10, 1883.

Wielowiejski, H. de. Observations sur la spermatogénèse des Arthropodes. (Archiv Slav. de Biologie, 1886, ii, pp. 28–36.)

Ballowitz, E. Zur Lehre von der Struktur der Spermatozoen. (Anat. Anzeiger, i Jahrg., 1886, pp. 363–376.)

—— Untersuchungen über die Struktur der Spermatozoen, zugleiche in Beitrag zur Lehre von feineren Bau der kontraktilen Elemente. Die Spermatozoen der Insekten. I. Coleopteren. (Zeitschr. f. wissensch. Zool., 1, 1890, pp. 317–407, 4 Taf.)

—— Zu der Mittheilung des Herrn Professor L. Auerbach in Breslau über merkwürdiger Vorgänger am Sperma von Dytiscus marginalis. (Anat. Anzeiger, 1893, viii Jahrg., pp. 505–506.)

—— Die Doppelspermatozoen der Dyticiden. (Zeitschr. f. wissensch. Zool., lxvi, 1895, pp. 458–499, 5 Taf.)

Beauregard, H. Note sur la spermatogénèse chez la cantharide. (Compt.-rend. Soc. Biol., Paris, 1888, iv, pp. 331–333.)

Gilson, G. Étude comparée de la spermatogénèse chez les Arthropodes, in La Cellule, Recueil de Cytologie et d’Histologie gén., i, 1888, 8 Pl.

Verson, E. Zur Spermatogenesis. (Zool. Anzeiger, xii Jahrg., 1889, pp. 100–103, Fig.)

—— La spermatogenesi nel Bombyx mori. (Padova, 1889, 25 pp. und 3 Taf.)

—— Zur spermatogenesis. (Zool. Anzeiger, xii, 1889, pp. 100–103.)

—— Zur spermatogenesis bei der Seidenraupe. (Zeitschr. f. wissens. Zool., lviii, 1894, pp. 303–313, 1 Taf.)

Henking, H. Ueber Reductionsteilung der Chromosomen in den Samenzellen von Insekten. (Internat. Monatsschr. f. Anat. und Phys., 1890, vii, pp. 243–248.)

—— I. Untersuchungen über die erste Entwicklungsorgänge in der Eiern der Insekten. II. Ueber Spermatogenese und deren Beziehung zur Eientwickelung bei Pyrrhocoris apterus. (Zeits. wissens. Zool., xlix, 1890, pp. 503–564; li, 1891, pp. 685–736.) III. Specielles und Allgemeines. (Ibid., 1892, liv, pp. 1–274, 12 Taf.)

Sabatier, A. De la spermatogénèse chez les Locustides. (Comptes rend. Acad. Paris, 1890, cxi, p. 797.)

Cholodkowsky, N. Zur Frage über die Anfangsstadien der Spermatogenese bei den Insecten. (Zool. Anzeiger, 1894, pp. 302–304.) See also Zool. Anzeiger, 1892, p. 179.

Auerbach, Leopold. Ueber merkwürdige Vorgänge am Sperma von Dytiscus marginalis. (Sitz. Ber. Akad., Berlin, 1893, pp. 185–203, 2 Figs.)

—— Zu dem Bemerkungen des Herrn Dr. Ballowitz betreffend das Sperma von Dytiscus marginalis. (Anat. Anzeiger, viii Jahrg., 1893, pp. 627–630.)

Toyama, K. On the spermatogenesis of the silkworm. (Bull, ii, No. 3, Coll. Agric. Imp. Univ. Tokyo, pp. 125–157, 1894, 2 Pls.)

Wilcox, E. V. Spermatogenesis of Caloptenus femur-rubrum and Cicada tibicen. (Bull. Mus. Comp. Zool., xxvii, 1895, pp. 32, 5 Pls.)

—— Further studies on the spermatogenesis of Caloptenus femur-rubrum. (Ibid., xxix, 1896, pp. 193–202, 3 Pls.)

Wilson, Edmund B. The cell in development and inheritance. (New York, 1896.) Also the writings of Platner, Waldeyer.

d. On the paired genital efferent passages

Loew, H. Abbildungen und Bemerkungen zur Anatomie einiger Neuropterengattungen. (Linnæa Ent., 1848, pp. 345–385, 6 Taf.)

Meinert, F. Anatomia Forficularum, i, Kjöbenhavn, 1863, 1 Pl.

—— Om dobbelte Saedgange hos Insecter. (Naturhist. Tidsskrift, 3 Raekke, v, 1868, pp. 278–294.)

Palmén, J. A. Zur vergleichenden Anatomie der Ausführungsgänge der Sexualorgane bei den Insekten. (Morph. Jahrb., ix, 1883, pp. 169–176.)

—— Ueber paarige Ausführungsgänge der Geschlechtsorgane bei Insekten. Eine morphologische Untersuchung. Helsingfors, 1884, pp. 108 und 5 Taf.

Nusbaum, J. Zur Entwicklungsgeschichte der Ausführungsgänge der Sexualdrüsen bei Insekten. (Kosmos, Lemberg, 1884, ix Jahrg., pp. 256–266, 393–408, 462–474, 2 Taf. In Polish with résumé in German.)

Spichardt, C. Beitrag zur Entwickelung der männlichen Genitalien und ihrer Ausführgänge bei Lepidopteren. (Verhandl. d. naturwiss. Vereins zu Bonn, 1886, xliii Jahrg., pp. 1–34, 1 Taf.)

Jackson, W. H. Studies in the morphology of the Lepidoptera. I. (Zool. Anzeiger, xii Jahrg., 1889, pp. 622–626.) (See p. 389.)

Lowne, B. Th. On the structure and development of the ovaries and their appendages in the blow-fly (Calliphora erythrocephala). (Journ. Linn. Soc. London, 1889, xx, pp. 418–442, 1 Pl.)

See also Meinert (1897), Heymons (1897).