SEVENTH ANNUAL REPORT. 113 
of the diseased area are surrounded by a pronounced infiltration 
of small round and occasional plasma cells, and many of them 
are completely occluded by fibrous tissue which has developed 
about them, chiefly in the adventitia. 
“Groups of the Mischerschen Schleuche are frequent in the 
muscle cells, and a few are found in the fibrous tissue, apparently 
remaining after absorption of the muscle cells in which they were 
originally lodged.” 
Apparently this aneurism of the heart was formed by degen- | 
eration of the muscle cells in this particular area, probably pri- 
marily due to the presence of the Mischerschen Schleuche, with 
fibroid replacement of the muscle tissue as degeneration pro- 
gressed. It is also probable that the condition was favored by 
the inflammation which may accompany the encystment of the 
schleuche. It is possible, however, that the original lesion was 
thrombosis of the left coronary artery with consequent muscular 
degeneration and fibroid replacement. This is the more common 
cause of aneurism of the heart in the human. In so far as I am 
able to learn, this case is absolutely unique. 
MUSCULAR ATROPHY. 
One of the most remarkable specimens obtained during the 
past year was that of a beaver, which showed very pronounced 
atrophy of the muscles of the rear extremities. The character 
of the lesions in this case differs entirely from those of ordinary 
muscular atrophy, and its causation is a complete riddle to us. 
No history was, of course, obtainable, and unfortunately neither 
the spinal cord nor the peripheral nerves were secured for ex- 
amination. 
DEATH FROM INJURIES. 
Fortunately, the number of deaths from injury has been very 
small. This is a most excellent showing, especially where so 
large groups of animals are kept together as is the practice with 
us. But eight deaths resulted from this cause. 
CAUSE OF DEATH UNKNOWN. 
We have been able to establish the cause of death in all re- 
corded cases except four. In this regard I must especially com- 
mend the industry and thoroughness of Dr. Blair, to whom the 
major part of this work has been entrusted. 
