428 VEDDER AND CLARK. 



The relation betiveen the amount of polished rice eaten and 

 the development of neuritis. — It has been generally observed 

 that the great majority of the fowls fed on polished rice usually 

 lose their appetites after about a week on this diet, and there- 

 after eat only small amounts of rice. There are always a few 

 fowls, however, which eat greedily up to the very last, and 

 will eat far greater amounts than the usual ration allowed (120 

 grams). Several deductions have been drawn from this fact 

 with regard to the development of neuritis. Some observers 

 have thought that those fowls that have eaten well throughout 

 the experiment have been protected from the development of 

 the disease by this , increased consumption of rice and, therefore, 

 have been inclined to regard polyneuritis as the result of simple 

 inanition. On the other hand, other observers have thought that 

 those fowls that ate the most rice developed the disease soonest, 

 and have regarded this as an argument in favor of the theory 

 that polyneuritis is caused by some toxin contained in the 

 polished rice. We have observed fowls that always ate well, and 

 yet developed neuritis sooner than usual ; we have observed other 

 fowls that ate large quantities of rice throughout the experiment, 

 but whose incubation period was longer than normal. Again, 

 some of the fowls that have eaten poorly have developed neuritis 

 promptly, while others have not developed the disease at all. 

 Therefore, it is believed that the amount of rice eaten has little 

 to do with the development of the disease, which depends rather 

 on the idiosyncrasy of the fowl with regard to the amount of 

 neuritis-preventing substance required. 



II. OBSERVATIONS ON PATHOLOGY. 



Eijkman, Fraser and Stanton, Chamberlain and Vedder, and 

 others have described degeneration in the sciatic nerves of the 

 domestic fowl after a prolonged diet on polished rice. The 

 questions as to whether the condition is a general nervous affec- 

 tion or a peripheral neuritis, as to the extent of the degenerative 

 changes, the selective localization of the affection, the place of 

 onset of the neuritis and regeneration have led us, in addition 

 to what has been said above, into a study of the minute anatom- 

 ical changes which may take place in the nervous system in 

 such fowls. 



A microscopic study was first made of those nervous elements 

 in which the degenerative changes are probably first manifested 

 and in which these changes are most apparent, that is, the 

 peripheral nerves. This, as might well be expected, increased 

 our interest in the more obscure changes. 



