THE SWAMP FEVER OF HORSES. 
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enlarged and congested. The prevertebral lymph glands from the lumbar 
region are also enlarged and congested ; the thyroid, parathyroid, parotid 
and submaxillary glands are normal. The brain, spinal cord, and bone 
marrow are normal in appearance. The intestines are normal ; they con- 
tain a few Sclerostomum tetracanthum. The swelling on the hind legs is 
due to a thick layer of extremely firm, fibrous tissue. The joints are 
unaffected and there is no sign of recent inflammation. 
(b.) Minute appearances. — Heart: Markedly injected; otherwise nor- 
mal. Lung : There is very marked injection. The alveolar capillaries con- 
tain numerous phagocytic cells with blood corpuscles, pigment and poly- 
morphonuclear leucocytes as inclusions. A few veins have small elevations 
of the intima caused by collections of large mononuclear cells containing 
light brown pigment, and lymphoid and plasma cells. In one instance there 
is a thrombus attached to one of these lesions. A portion of one section is 
composed of collapsed alveoli with greatly distended capillaries in the 
tortuous walls. The small bronchi are collapsed but do not contain 
exudate. Throughout the sections there are numerous cells containing 
light brown pigment, distributed chiefly in the alveolar capillaries and 
about small veins and arteries. Spleen : The secondary follicles are 
normal. The pulp is moderately injected and contains large quantities of 
light brown pigment in the form of spherules and granules packed in 
cells. There are numerous phagocytes attached to the reticulum which 
contain chiefly lymphoid cells. Liver: There are very many small foci 
of infiltration with lymphocytes and phagocytic cells, the latter containing 
pale brown pigment. In these foci there are often a few necrotic liver 
cells and polymorphonuclear leucocytes, but for the greater part these 
foci seem to lie between the liver columns and sinusoids and do not con- 
tain degenerated liver cells. The organ is considerably congested. 
There is a very slight increase of connective tissue about the portal canals. 
In many places there is a thin layer of hyaline material between the liver 
columns and sinusoids. The bile ducts and vessels are normal. Pan- 
creas : There are occasional small areas of fibrosis in the lobules, other- 
wise the organ is normal. Kidney: The glomeruli are injected but are 
otherwise normal. There are foci of marked parenchymatous degenera- 
tion of the convoluted tubules ; in these areas there are a few immigrating 
polymorphonuclear leucocytes. Some of the collecting tubules contain 
hyaline casts and leucocytes. There is a small amount of greenish brown 
pigment in the epithelium of the tubules. Adrenal: Normal. Thyroid: 
Contains traces only of colloid material. Parathyroid: Normal. Salivary 
gland : Normal. Muscle : Muscle fibers from the chest wall, esophagus, and 
one of the skeletal muscles contain Sarcosporidium ; none are seen in muscle 
from two positions in the diaphragm. In the muscle from the bruised 
area on the chest there are abscess cavities and suppurating tracts con- 
taining clumps of bacteria (cocci in chains and pairs) . In many places 
granulation tissue surrrounds the pus cavities. Esophagus : Mucosa and 
wall normal, except for Sarcosporidium in the striped muscle coat. 
Lymph glands : Five sections show hemolymph glands which are negative. 
