56 DISEASE IN WILD MAMMALS AND BIRDS 
two ungulates and one marsupial, probably incidental to 
fright when being caught by the keepers. 
The association of secondary dilatation with hyper- 
trophy is only evident in three instances. One case and 
perhaps the most interesting, is that in which the princi- 
pal antecedent pathology was thyroid hyperplasia and 
nephritis; the dilatation was perhaps agonal or shortly 
before the last struggles. It would seem that all of the 
dilatations occurred shortly before death because long 
standing passive congestions and dropsies of cardiac 
origin are exceedingly rare; only one certain case is 
recorded (carnivore). 
Let us now examine the Table (2) according to orders 
and then as to causation. The Primates ' heart is appar- 
ently well able to increase in size in response to increased 
work, a demand most often made by pulmonary, pleural 
and pericardial diseases. Two of these cases occurred in 
animals suffering with pulmonary tuberculosis suffi- 
ciently extensive to impede cardiac action while in 
another case the tuberculous lesion was mild but a peri- 
carditis existed. When the right hand columns are 
inspected it would seem that on occasion dilatation may 
occur; one of the tuberculous pulmonary cases had a 
dilated heart. The slothful lemurs apparently have no 
call upon their cardiac mechanism. 
Carnivora with their large organ, which, it would 
seem, should be prepared for excess work either simply 
as a reserve or as an inherent ability to grow, 
present in about equal numbers, hypertrophy and dilata- 
tion. It is admitted that there are within this order, 
genera of differing habits, but analysis of the canidas, 
f elidae and ursidaj for examples, in the first place, offer too 
few specimens for conclusions and, secondly, have upon 
trial actually shown nothing definite, so that we are 
forced to use the larger group, the order. It is interest- 
ing to note that long continued infection is in this order 
the most potent factor in enlargements of the heart. Four 
