THE SWAMP FEVER OF HORSES. 
223 
Heart (loi pounds) : The valves and endocardium are normal ; 
the myocardium is firm and pale, but uniform in color and consistency; 
the aorta is normal. Lungs (right, 6h pounds; left, 7 pounds): Both 
are normal. The bronchial lymph glands are not enlarged ; there is 
marked edema of the mediastinal tissues. Spleen (4 pounds) : Capsule 
seems slightly thickened; the substance is firm. Liver (26^ pounds): 
Appears to be normal. Gastro-intestinal tract: The mucosa is normal. 
The colon contains many Sclerostomum armatum ; in the cecum one of 
these worms was found in a small submucosal abscess. Pancreas : 
Normal. Kidneys (together 5^ pounds) : Both kidneys are similar in 
appearance ; the cortices are translucent and yellowish ; the papillae of 
the pyramids are prominent but colorless, their bases are pale red, the 
apices yellow and translucent ; the pelves are edematous. Adrenal glands: 
Both normal. Bone marrow : That of the long bones is yellow and fatty ; 
that from the short bones is firm and dark red. Brain and spinal cord : 
Normal. 
(b) Minute appearances. — Heart: Normal. Lung: Moderately in- 
jected. The alveolar walls are slightly tortuous, the capillaries are 
filled with blood and, in foci, are packed with cells* Some of the cells 
are phagocytic and contain red corpuscles, brown pigment, or nuclear 
remains. There are other groups of cells with basic-staining protoplasm 
and nuclei resembling those of lymphocytes. Throughout the sections 
there is much light brown pigment in granules in the alveolar capillaries, 
within cells, and, apparently, lying free. In a number of veins of large 
size there are collections, beneath the intima, of large mononuclear cells 
containing masses of light brown pigment, and, occasionally, clusters of 
delicate rod-shaped crystals. The cell masses produce elevations pro- 
jecting into the lumen of the vessels. The pleura and interlobular septa 
show evidences of slight edema. Spleen : Moderately injected ; other- 
wise normal. Liver: There is very extensive central necrosis through- 
out the organ and the lesions present various stages of the process, the 
earliest being represented by masses of hyaline, degenerated liver cells. 
The later stages show complete absence of liver cells in the centers of 
lobules with regenerative processes, evidenced by mitosis in liver cells at 
the periphery. Polymorphonuclear leucocytes are few in number ; the 
collections of cells consist chiefly of lymphocytes and phagocytic cells 
which contain bile pigment and light brown refractive pigment. Through- 
out the liver there are collections of lymphocytes and mononuclear cells 
in the sinusoids. The bile ducts and vessels are negative. No bacteria 
were seen in sections stained by Gram's stain or by methylene blue and 
eosin. Many endothelial cells of the sinusoids throughout the liver con- 
tain light brown pigment. The portal spaces contain collections of 
lymphocytes. Pancreas: Normal. Kidney: Many glomeruli are nearly 
bloodless, because of the obstruction of the capillaries by cells ; these 
cells are large, mononuclear ones, and many contain light brown pigment. 
Occasionally there are among them a few polymorphonuclear leucocytes 
and large cells containing hyaline drops. The tubules show slight 
