32 
pneumonia. Many but not all of the birds had Heterakis 
in the ceca. 
The process seemed to start as a focal necrotizing lesion 
in the mucosa or submucosa of the ileum just above the 
ceca and colon; many had lesions in the ceca and as far 
down the colon as the cloacal dilatation. Among the 
animals dying late in the epidemic several showed lesions 
involving the whole small intestine, a few indeed with 
greater involvement of the duodenum than of the lower 
parts. 
Judging from the gross and microscopal appearances 
it seems that the virus causes at first a cellular infiltrate 
in the mucosa or submucosa upon which necrosis shortly 
supervenes. The overlying mucosa soon degenerates, 
and the surface is covered with an indefinite slough. In 
other cases, especially early in the epidemic, the process 
extended outward and appeared as muscular or sub- 
peritoneal necrotic areas before the mucosa was much 
involved. At all events necrosis was an early change 
in every case. The blood vessels were usually throm- 
botic. In the cases that spread toward the peritoneum 
a plastic peritonitis of varying severity was present. 
The focal liver lesions were not present in every case. 
They took the form of focal necroses or abscesses. Some 
fatty or parenchymatous degeneration was always 
present. The liver lesions probably started as in- 
flammations of the veins from which necrotizing or 
infiltrative lesions spread. 
The splenic changes were those of lymphoid hyper- 
plasia, only distinctive in the enormous number of large 
lymph-cells. Typical microscopical changes are as fol- 
lows, quoted from one of the autopsy protocols. 
The lung showed moderate congestion with here and 
there a little epithelial swelling and a mild bronchitis 
and peribronchitis. The type of bronchitis is infiltra- 
tive rather than catarrhal. The heart muscle showed 
granular degeneration of the fibers with breaking up or 
irregularity of the striae. Some increase in interfibrillar 
nuclei and especially those of the capillaries. There is 
