DISEASES OF THE HEART 53 
acute cases were combined with some evidence of generaJ 
septicemia. The type of lesion was in no way peculiar, 
unless the facts that all were vegetative when acute and 
markedly deforming when chronic, be noteworthy. In two 
chronic aortic cases the valvular orifice was almost closed, 
yet the left ventricle could not be considered as greatly 
hypertrophied and no dilatation existed. In one acute 
aortic and mitral case, general dilatation existed. 
The mitral was involved nine times, three times alone, 
four times with the aortic, once each with the tricuspid 
and pulmonary. Once the vegetations were limited to 
the mural endocardium. Nine of these animals came from 
one enclosure over a period of two and a half years, dur- 
ing which time other opossums died from similar bacterial 
infections (pneumonia) despite repeated cleansing of the 
place. No unusual number of cases of this or similar 
kinds occurred elsewhere in the Garden at this time, but 
it would seem that we had in this cage a continued bac- 
terial infection. 
Unusual Pericardial Changes. 
The appearance of a stiif gelatinous exudate in the 
pericardial sac has attracted our attention on ten 
occasions (8 birds, 2 mammals). The substance seems 
quite homogeneous and almost entirely acellular. One 
specimen became solid on heating and another became 
turbid when put into Kaiserhng's fluid. In two cases bac- 
terial cultures were made ; nothing grew. It has not been 
associated with tuberculosis or tumors nor has any one 
pathological lesion more than another appeared to 
accompany it. 
A peculiar lesion occasionally seen in birds is ''uratic 
pericarditis" a process not infectious at all, according to 
Plimmer, but due to renal disease. It has been seen here 
in association with retention of urates in the kidney, with 
gout of birds, and apparently quite independent of any 
renal or constitutional disease. Both layers of the sac 
