DISEASES OF THE HEART 49 
will be shown later when after discussing the pathological 
anatomy of the heart in the wild mammals and birds, we 
can study these changes in light of statistics upon the 
relative size of the heart. 
Expression of Caediac Disease. 
The diseases of this organ are known only by their 
physical effects, chiefly by causing physical or functional 
defects in other organs and to a minor degree by purely 
physiological irregularities in the heart itself (tachy- 
cardia, arrhythmia). All the latter and most of the 
former are subjects discovered by observation during 
life and unfortunately cannot be included in the study 
at hand. Both states are well known to the veterinarian 
who diagnoses them with reasonable ease in animals that 
can be handled ; I saw one case of arrhythmia in a monkey 
for which no adequate gross morbid explanation was 
found postmortem. Some of these functional abnor- 
malities are certainly caused by myocardial disease and 
cardiac failure has occurred among many orders. An 
interesting observation was made by Plimmer (2) on sev- 
eral large birds (ostriches, storks, cassowaries) which 
apparently died from this condition ; at autopsy he found 
myocardial degeneration, or epicardial edema or only a 
flabby heart. Lack of exercise was held responsible by 
this observer. Such cardiac deaths have probably been 
encountered at this Garden but we have accounted them to 
shock, or gastrointestinal disease; this matter will be 
discussed on a later page. 
Coronary Artery Disease. 
If a degenerative sclerosis of coronary vessels be the 
cause of angina pectoris then perhaps paroxysms of this 
kind occur, for we have seen such anatomical changes in 
the heart of three widely separated varieties of animals, 
a Nylghaie, a Hamadryas Baboon, a Macaque, and a 
Brown Pelican. The history of these animals does not 
(2) Proe. London Zool. Soc, 1907. 
