The unfitness of certain substances for assimilative purposes is manifest by the anaphylactic symptoms that so frequently follow their use. Alimentary anaphylactic phenomena are confined almost exclusively to substances of animal origin. The more closely these animal substances resemble the human body in composition, the more frequently do they give rise to these phenomena. Thus flesh is the worst offender, eggs come second and milk is last.

Little can be said in defense of the use of animal foods except in instances of dire necessity. Let us consider them briefly.