Wright’s Theory.—According to this view a bacillus which was given off in the faeces was ingested and locating in the duodenal mucosa gave off a toxin similar to that of the diphtheria bacillus. Instead of developing its soluble toxin in the membrane of the region of the throat this action took place in the upper part of the small intestines.
Of the bacterial causes may be mentioned: (1) The coccus of Pekelharing and Winckler. This organism was supposed to be short lived in the body and repeated infections were necessary to produce the disease.
(2) Dangerfield held views somewhat similar to those of Pekelharing and thought a coccus in the alimentary canal the cause.
(3) Isuzuki regarded a coccus isolated from the urine as the cause.
(4) Okata and Kokubo thought a coccus obtained from the blood to be the infecting agent.
Various bacilli, other than that incriminated by Wright, have been brought forward as pathogenic agents but it may be stated without further discussion that the claims of the advocates of bacterial causes have not been verified and are solely of historical interest. The same statement will hold for the plasmodium-like protozoon of Glogner which was found in the splenic blood.
Of the chemical theories may be mentioned; (1) Arsenic poisoning. In an outbreak of arsenical neuritis in England, from arsenic contained in the glucose used in making beer, Ross diagnosed the illness as beriberi. Subsequently, arsenic was found in the hair of certain patients with beriberi, hence the theory which has never been substantiated. It may be stated that a careful study of this epidemic by Reynolds and Bury indicated that the alcoholic factor was also operative as persons taking an equal amount of arsenic but without alcohol, did not develop neuritis.
(2) Treutlein’s oxalate theory.—This was based on the fact that polyneuritis gallinarum could be produced in fowls by feeding them oxalic acid.
Of the food deficiency theories, the most prominent is (1) that of Takaki, generally designated the nitrogen deficiency theory. As the result of increasing the proteid constituents of the ration of the Japanese Navy from 109 to 196 grams, the disease was largely eliminated (from about 32% incidence to less than 0.5%).
In the old ration the ratio of N to C was as 1 to 17—32, in the new ration, 1—16. In looking over the constituents of the new ration the addition of about 100 grams of beans is noted. These are rich in vitamines.