42 CIRCULATION OF THE BLOOD. 



direction and consequently project the entire organ against the walls of the chest. This 

 movement is aided by the recoil of the ventricles as they discharge their contents. The 

 displacement of the heart during its systole has long been observed in vivisections and 

 may be demonstrated in any of the mammals. The most interesting observations on 

 this point are those of Chauveau and Faivre, which were made upon a monkey. In this 

 animal, in which the position of the heart is very much the same as in the human sub- 

 ject, the locomotion of the organ was fully established. 



Twisting of the Heart. The spiral course of the superficial fibres would lead us to 

 look for another phenomenon accompanying its contraction ; namely, twisting. If we 

 attentively watch the apex of the heart, especially when its action has become a little 

 retarded, there is a palpable twisting of the point upon itself from left to right with the 

 systole, and an untwisting with the diastole. 



Hardening of the Heart. If the heart of a living animal be grasped by the hand, it 

 will be observed that at each systole it becomes hardened. The fact that it is composed 

 almost exclusively of fibres, resembling very closely those of the voluntary muscles, 

 explains this phenomenon. Like any other muscle, it is sensibly hardened during con- 

 traction. 



Shortening and Elongation of the Heart. The phenomena which we have just de- 

 scribed are admitted by all writers on physiology and can easily be observed ; but the 

 change in length of the heart during its systole has been a matter of discussion. All who 

 have studied the heart in action have observed changes in length during contraction and 

 relaxation ; but the contemporaries of Harvey were divided as to the periods in the heart's 

 action which are attended with elongation and shortening. Harvey himself is not abso- 

 lutely definite on this point. In one passage he says, in describing the systole, " that it is 

 everywhere contracted, but especially towards the sides, so that it looks narrower, a lit- 

 tle longer, more drawn together." In his description of the case of the son of the Vis- 

 count Montgomery, who suffered from ectopia cordis, he states that during the systole 

 the heart "emerged and protruded." Vesalius, Fontana, and some others, contended for 

 elongation during the systole ; but Haller, Steno, Lancisi, and Bassuel stated that it be- 

 comes shortened. The view generally entertained at the present day is that the heart is 

 shortened during its systole. There is no doubt that the point of the heart is protruded 

 during the ventricular systole, but this protrusion is not due to elongation of the ventricles. 

 By suddenly cutting the heart out of a warm-blooded animal and watching the phenom- 

 ena which accompany the few regular contractions which follow, it is seen that the ven- 

 tricles invariably shorten during the systole. This can easily be appreciated by the 

 eye, but more readily if the point of the organ be brought just in contact with a plane 

 surface at right angles, when, at each contraction, it is unmistakably observed to recede. 

 The following experiments we have frequently repeated before the class of the Bellevue 

 Hospital Medical College, and have satisfied ourselves of their accuracy. A large New- 

 foundland pup, about nine months old, was poisoned with woorara, artificial respiration 

 was kept up, and the heart exposed. After showing the protrusion of the point and 

 the apparent elongation of the heart while in the chest, the organ was rapidly removed, 

 placed upon the table, and confined by two long needles passed through the base, pinning 

 it to the wood. It contracted for one or two minutes, and at each systole the ventricles 

 were manifestly shortened. The point was then placed against an upright, and it re- 

 ceded with each systole about an eighth of an inch. This phenomenon was apparent to 

 all present. In another experiment, performed a few weeks later, the heart, which had 

 been exposed in the same way, was examined in situ, by pinning it with two needles to 

 a thin board passed under the organ. The presence of the needles did not seem to in- 

 terfere with the heart's action, and, at each ventricular systole, the point evidently 

 approached the base. To render this absolutely certain, a knife was fixed in the wood 



