STUDY OF POLYNEURITIS GALLINARUM. 431 



Cha7iges in the heart. — Following our own observations that 

 in those fowls showing symptoms of peripheral neuritis or pros- 

 tration tlje vagus showed a greater or less degree of degenerative 

 change, an examination was made of the heart. In the gross, 

 the heart showed little or no change from normal. Hypertrophy 

 was not observed. There was an absence or diminution of fat 

 beneath the pericardium. In most cases the myocardium was 

 of a lighter hue than normal. Pericardial fluid was never pres- 

 ent in great excess. Aside from those cases of extreme pros- 

 tration before death, oedema was not noticed. In some of these 

 latter cases a slight oedema was observed beneath the peri- 

 cardium at the base of the heart. Microscopically, in the hearts 

 of those fowls dead after prostration there was little to be 

 observed which would indicate a pathological change in the 

 musculature. A few fibers here and there were seen in the 

 myocardium of the ventricles in which the cross striation was 

 more or less obscure and which stained poorly. An apparent 

 increase in pigment was also noted in several hearts. At most, 

 we would hesitate to claim any changes further than those which 

 would indicate beginning parenchymatous or mucoid degenera- 

 tion. In those fowls which presented chiefly the symptoms of 

 peripheral neuritis it was even more difficult to observe changes 

 which could be considered pathological, and in some cases no 

 change whatever was to be noted. 



Degeneration in the peripheral nerves. The vagiis. — Degen- 

 erative changes, as shown by the Marchi method, were observed 

 in all the cases examined. Plate III, figs. 5 and 6, illustrates 

 high- and low-power photomicrographs of a vagus nerve showing 

 degeneration stained by Marchi's method. Unlike the sciatic 

 nerve, however, the extent and degree of degeneration in the 

 vagus did not always correspond to the severity of the symptoms 

 before death, nor was the most extensive degeneration to be seen 

 in the vagus nerve of those cases which showed prostration. 

 Fowls in good general condition sometimes showed extensive 

 degeneration in the vagus. Likewise, we were not able to 

 establish an interrelation between the severity of the degenera- 

 tion in the vagus and the amount of pathologic change in the 

 heart. 



That there may be no interrelation between the severity of 

 nervous symptoms and the systemic condition of the animal 

 before death on the one hand and the degree or extent of degen- 

 eration found in the vagus nerve on the other is well showTi 

 by the following four cases : 



Fowl 3 showed symptoms of veiy little peripheral neuritis 



