THE HEART. 275 



such. It is, however, a phenomenon precisely similar to that which 

 takes place in the contraction of a voluntary muscle, which becomes 

 swollen and indurated at the same moment and in the same propor- 

 tion that it diminishes in length. 



2. At the time of contraction, the ventricles elongate and the 

 point of the heart protrudes. This phenomenon was very well 

 described by Dr. Harvey. 1 " The heart," he says, " is erected, and 

 rises upward to a point, so that at this time it strikes against the 

 breast and the pulse is felt externally." The elongation of the 

 ventricles during contraction has, however, been frequently denied 

 by subsequent writers. The only modern observers, so far as we 

 are aware, who have recognized its existence, are Drs. C. W. Pen- 

 nock and Edward M. Moore, who performed a series of very careful 

 and interesting experiments on the action of the heart, in Philadel- 

 phia, in the year 1839. 2 These -experimenters operated upon calves, 

 sheep, and horses, by stunning the animal with a blow upon the 

 head, opening the chest, and keeping up artificial respiration. They 

 observed an elongation of the ventricle at the time of contraction, 

 and were even able to measure its extent by applying a shoemaker's 

 rule to the heart while in active motion. We are able to corroborate 

 entirely the statement of these observers by the result of our own 

 experiments on dogs, rabbits, frogs, &c. The ventricular contrac- 

 tion is an active movement, the relaxation entirely a passive one. 

 When contraction occurs and a stream of blood is thrown out of 

 the ventricle, its sides approximate each other and its point elon- 

 gates ; so that the transverse diameter of the heart is diminished, 

 and its longitudinal diameter increased. This can be readily felt 

 by grasping the base of the heart and the origin of the large vessels 

 gently between the first and middle fingers, and allowing the end 

 of the thumb of the same hand to rest lightly upon its apex. 

 With every contraction the thumb is sensibly lifted and separated 

 from the fingers, by a somewhat forcible elevation of the point of 

 the heart. 



The same thing can be seen, and even measured by the eye, 

 in the following manner : If the heart of the frog or even of any 

 small warm-blooded animal, as the rabbit, be rapidly removed from 

 the chest, it will continue to beat for some minutes afterward ; and 

 when the rhythmical pulsations have finally ceased, contractions 



1 Works of William Harvey, M. D. Sydenham ed., London, 1847, p. 21. 



2 Philadelphia Medical Examiner, No. 44. 



