ments on the effect of sunlight on animals fed on a too restricted (unphysiological) diet have been advanced recently; but it is evident from what we now know of the seasonal, epidemiological, and topographical habits of pellagra that such an hypothesis is untenable.
It would be idle to discuss the arguments brought forward to show that pellagra is caused by bad water, insanitary dwellings, poverty, syphilis, leprosy, rancid oil, sour milk, acid wine, bad cheese, rye, millet, buckwheat, common salt, onions, or garlic. The maize theory, on the other hand, demands,because of its popularity, a searching scrutiny.
The general opinion is that pellagra appeared soon after the introduction of maize into Europe, and that it advanced pari passu with the extension of maize cultivation, and with the more general adoption of the new cereal as an article of food. For these and other reasons maize is still held by many to be the causative agent of pellagra, just as a condition of rye is known to be the cause of ergotism; and, as in the latter case, various theories have been advanced to explain the operation of the assumed cause.
The morbific action of maize has been variously attributed to —
- (a) Deficiency in its nutritive principles.
- (b) Specific toxic substance contained normally in the grain.
- (c) Poisons elaborated after it has been ingested.
- (d) Toxic substances elaborated during decomposition of the grain.
- (e) Fungi or bacteria found on maize.
(a) Deficiency in nutritive principles.— Maize stands high as regards alimentary value. Insufficient nourishment may bring about inanition and marasmus, but never causes specific lesions like those of pellagra. Entire populations who live solely on rice or potatoes remain quite free from this disease, although these foods are far inferior to maize in nutritive value.
(b) Specific toxic substances normal to maize.— Those who advanced this theory were obliged to stipulate for a special personal susceptibility, otherwise the immunity of the millions who live on Indian corn could not be accounted for.
(e) Poisons elaborated from maize within the alimentary canal.— Neusser regards pellagra as a peculiar form of auto-intoxica-
