104 THE VITAMINES 



paralysis is noted. These changes arise after 7 days of rice feeding. 

 The number of degenerated fibers bears no relation to the severity 

 of the paralysis. Cases of -light clinical symptoms often display 

 marked degeneration, while severe cases frequently show only from 

 4 to 10 per cent of degenerated fibers. As a rule, from 10 to 15 per 

 cent of the total fibers are found changed. Schnyder (286) on the 

 contrary, finds only slight degeneration in birds and' believes, 

 because of the therapeutic influence of the vitamine, that the paresis 

 could not be the result of degenerative processes in the brain. We 

 have frequently pointed out that if we kill an animal a few days 

 after it has been cured with vitamine, and make a histological study 

 of the nerves, the degenerated fibers are still to be seen and persist 

 for a long time. In the meantime, the normal fibers appear to 

 assume the functions of the diseased fibers. 



The nerves, histologically examined, give the following picture: 

 According to Kimura, the first indication of degeneration is to be 

 sought for in the axis cylinder, while the earlier prevalent idea was 

 that the signs of degeneration are first noted in the medullary sheath; 

 the myelin sheath, according to Kimura, may remain intact. How- 

 ever, as soon as the latter degenerates, the axis cylinder can no longer 

 be differentiated. The myelin fragments thereupon are resorbed 

 in situ through the cells of Schwann's sheath. If a degenerated 

 myelin fiber still contains an axis cylinder, it is a regenerated axis 

 cylinder from the ribbon-like protoplasm. The new cylinder is 

 smooth and fragile and resembles that seen after a trauma. 



The same changes are also to be noted in the dorsal and ventral 

 nerve roots, as in all the dorsal strands of the spinal cord. Further, 

 changes are apparent in the cells of the forward and rear horns of the 

 lumbo-sacral cord; here the tigroid bodies are invisible, and the 

 stainable substance (Nissl's method) accumulates over the axis 

 cylinder. In some cases, the nuclei are weakly colored. Similar 

 pathological nerve studies were made by Weill and Mouriquand (287) , 

 Kato and Shizume (288) and Paguchi (289). 



The muscles. The muscles exhibit atrophy and fatty degeneration, 

 but the changes disappear rapidly on returning to normal nutrition. 



The heart. In most cases, this is unchanged; only seldom is there 

 any edema, pigmentation, and traces of parenchymatous degenera- 

 tion. Hypertrophy of the right heart, as in human beriberi, does not 

 take place in chickens. On the contrary, we have personally seen 



