W. ZUILL. 
162 
cle. 3—Tempo; disatole of the four cavities, relaxation, pause. 
This is a short moment of rest in the continual action of the 
heart, which is, however, indistinct and hardly perceptible: 
Chauveau and Marey have graphically represented the rhythm 
of the action of the heart by means of an apparatus which they 
applied on horses, connecting the right ventricle through the 
jugular vein. The knowledge of the variation of pressure is of 
eminent importance for the diagnosis of heart disease. 
Whereas, the systole is noticed in all the cavities of the heart 
by a sudden and convulsive contraction of the muscular walls; 
the diameter of the ventricle appears to be shortened during sys¬ 
tole, and the heart becomes more round, while during diastole it 
is oval. During this procedure the form and position are there¬ 
fore changed, inasmuch as the heart turns from left to right upon 
its longer axis. The apex of the heart rises somewhat from the 
sternum, approaches the base of the heart, and is stationed under 
the centre of the latter. Through the now accomplished relaxa¬ 
tion of the muscular fibres the diastole is noticed in all the cavi¬ 
ties of the heart. The muscles do not retain their acquired 
shortness caused by the active contraction, but again assume the 
length which they had before the contraction. Furthermore, 
the enlargement of the relaxed chambers is supported by the 
pressure which the blood, forced into the ventricle, exercises dur¬ 
ing the systole of the auricle. 
(To be continued .) 
CONTAGIOUS PLEURO-PNEUMONIA. 
Thesis presented by W. Zuill, D.Y.S., before the University of Pennsylvania, 
Medical Department. 
( Continued from page 107.) 
This disease, beiug one in which the lesions are entirely con¬ 
fined to the chest cavity, the pleura is naturally the only serous 
membrane from which effusion takes place, and here they are 
most marked, as it is most uncommon to find a large collection of 
fluid in this place, which seriously complicates the disease. This 
