DISEASES OF THE HEART 55 
hypertrophy be purely the building of a bigger engine or 
be accompanied by, or due to, muscular disease as had 
been suggested by certain authors, was a question to 
which an answer was hoped, but it would seem that the 
solution is no nearer than can be obtained in human 
pathology. Fifteen of the 34 cases showed some degree 
of myocardial damage. Some of the other cases may have 
been instances of so-called essential hypertrophy, 
enlargements due to hard work or to low-grade hidden 
infection. Aubertin (3) ascribes such cardiac muscle 
increase to overwork under the stimulus of intoxi- 
cation from intestinal sources or from irregular 
constitutional functions. For information concerning 
this and pathological enlargements one may consult the 
Table (2) of Hypertrophies and Dilatations; in advance 
the method of charting must be known. Since it is 
usually impossible to decide what may be the single 
important factor in the cardiac disease, all of the 
accredited factors have been listed with the hope that the 
resulting figures would be significant. Thus an animal 
may have recorded pericarditis, nephritis and arterio- 
sclerosis — ^who shall say which was primary or most 
potent in the cardiac change. 
Essential hypertrophy is limited to those cases for 
which there was no concomitant pathology that might 
have been responsible for the overgrowth. There was one 
in a carnivore (fox) and one in a raptatory bird (buz- 
zard). Idiopathic dilatations on the other hand are much 
more common, but they still bear a relation to the 
apparent vulnerability of the heart. Their distribition is 
as follows : Primates 1, Carnivora 1, Pinnipedia 1, Ungu- 
lata 1, Marsupialia 4, Anseres 1. These may be cases such 
as Plimmer described, of cardiac failure, indicated by 
dilatation, the result of inactivity. Besides these special 
instances and the ones accounted for in the list, there 
were three acute dilatations apparently due to shock, 
(3) Comptes Rendus 8oc. Biol, T, 62-206! 
