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. (2) According to Fales the hypothetical germ of beriberi can only live in body fluids deficient in potassium carbonate. The high content of potash in potatoes made him greatly increase the amount of this vegetable in the dietary he recommended. Fales noted scurvy as well as beriberi in the Bilibid prisoners on a diet deficient in potash. (3) Deficient fat. (4) Deficient phosphorus.—It was Schaumann’s idea that the phosphorus contained in the outer layers of the rice grain was essential in the prevention of beriberi. While it is now known that the beriberi-preventing substance does not contain phosphorus, yet the idea has proven of practical value as giving an index of beriberi-producing power of rice. _P_{2}O_{5} Index of Beriberi-producing Rice._—If a rice contain under 0.4% of phosphorus pentoxide it is liable to produce beriberi. Schaumann now considers that the antineuritic substance in rice polishings acts as an activator in the metabolism of phosphorus.