[1] An address prepared for the celebration of the fiftieth anniversary of the Massachusetts Board of Health, September, 1919.

[2] The administrative side of the subject is sketched in the next chapter.

[3] Reprint of Reports, Vol. I, p. 448.

[4] There is still no evidence to show that in the production of the excessive diarrhœa which prevails in insanitary districts, specific contamination of the filth accumulations is necessary.