920 ANIMAL PHYSIOLOGY. 
tion, he will have a broader basis for his cardiac physiology 
than is usual; and we think we may promise the medical stu- 
dent, who will in this 
and other ways that 
may occur to him 
supplement the usual 
work on the human 
cadaver, a pleasure 
and profit in the 
study of heart - dis- 
ease which come in 
no other way. 
With the view of 
assisting the obser- 
vation of the student 
as regards the heart 
of the mammal, we 
would call special at- 
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carried through the auricular appendage, hence the pension, chieny by 
i ethaia appearance due to the portions in relief cut its great vessels; the 
strong fibrous frame- 
work for the attachment of valves, vessels, and muscle-fibers; 
the great complexity of the arrangement of the latter; the 
various lengths, mode of attachment, and the strength of the 
inelastic chordee tendines ; the papillary muscles which doubt- 
less act at the moment the valves flap back, thus preventing 
the latter being carried too far toward the auricles, the pocket- 
ing action of the semilunar valves, with their strong margin 
and meeting nodules (corpora aurantii); the relative thickness 
of auricles and ventricles, and the much greater thickness of 
the walls of the left than of the right ventricle—differences 
which are related to the work these parts perform. 
The latter may be well seen by making transverse sections 
of the heart of an animal, especially one that has been bled to 
death, which specimen also shows how the contraction of the 
heart obliterates the ventricular cavity. ; 
It will also be well worth while to follow up the course of 
the coronary arteries, noting especially their point of origin. 
The examination of the valves of the smaller hearts of cold- 
blooded animals is a matter of greater difficulty and is facili- 
