STUDY OF POLYNEURITIS GALLINARUM. 447 



majority of the fibers show little or no advance over the preceding 

 stage. In those fibers from fowls which present symptoms of 

 neuritis and whose nerves show pronounced degeneration, the 

 stainable material takes on a more diffuse and somewhat homo- 

 geneous appearance in a majority of the fibers. Other fibers are 

 seen (10 to 15 per cent) which show an exaggeration of the 

 globular arrangement. These globules are more regular in shape 

 and oval in contour, and the stainable material shows a preference 

 for the periphery. These resemble very much the fibers which 

 show advanced degeneration by the Marchi method and are 

 probably identical with them. (Plate IX, fig. 18, fiber a.) Thus 

 it is evident that the fibers of the peripheral nerves of fowls on a 

 polished rice diet show an early (7-day or somewhat earlier) 

 change in their medullary sheath, and that in a varying percent- 

 age (10 to 15) this change is progressive and leads to the condi- 

 tion ordinarily termed degeneration. This can easily be followed 

 in Plate VIII, figs. 15 and 16, and Plate IX, figs. 17 and 18. 



IV. THE INFLUENCE OF VARIOUS ARTICLES OF FOOD ON THE PRODUC- 

 TION OF POLYNEURITIS GALLINARUM. 



In pursuing investigations into the cause of beriberi it has been 

 by no means uncommon to find instances in both experience and 

 the literature where beriberi has developed in spite of the fact 

 that the patients had received what was supposed to be a fairly 

 well-balanced ration containing rice as the staple article of diet. 

 This observation has been frequently urged as an insuperable 

 objection to the theory that beriberi is caused by rice diet. In a 

 previous paper (8) one of us has shown that fowls likewise de- 

 velop polyneuritis when fed on diet containing a sufficiency of all 

 the alimentary principles, provided no one of the ingredients of 

 this diet contains the neuritis-preventing substance. It is appar- 

 ent that the neuritis-preventing substance is not present in all 

 articles of food, and that, in those articles in which it is present, 

 it occurs in very variable amounts. It was, therefore, considered 

 desirable to test certain articles that are usually included in an 

 ordinary diet, in order to determine just what degree of protec- 

 tion they would afford when combined with a staple of polished 

 rice. 



The following experiments were perfprmed for this purpose: 



Experiment 29. — Four fowls were fed on polished rice, and in addition 

 were given daily 10 grams of raw potatoes. One fowl developed neuritis 

 in thirty-two days, 1 in thirty-eig'ht days, and the other 2 fowls re- 

 mained well after sixty-three days, when the experiment was discontinued. 



ExpeiHment SO. — Four fowls were fed on polished rice, and in addition 



