906 



SCIENCE. 



[N. S. Vol. V. No. 128. 



O71 the Relation between the Beat of the Ven- 

 tricle and the Flow of Blood through the 

 Coronary Arteries. W. T. Poetee. 

 When an isolated piece of dog's or cat's 

 ventricle is fed through the coronary artery, 

 the flow from the veins is seen to be greater 

 during systole than during diastole. In an 

 extirpated heart, supplied with blood at a 

 constant pressure through the coronary 

 arteries, a pulse synchronous with the sys- 

 tole may be observed in the superficial 

 auricular veins befoi-e and after their con- 

 nection with the coronary sinus is severed. 

 A similar but less marked pulse can be 

 demonstrated in the coronary arteries. 

 When a vein on the surface of a dog's ven- 

 tricle in situ in the living animal is in- 

 cised, and the heart slowed by vagus exci- 

 tation, the flow from the cut vein is much 

 increased during ventricular systole. These 

 observations show that the contraction of 

 the cardiac muscle compresses the veins, 

 and to a less extent the arteries, in the 

 substance of the heart. The systole must, 

 therefore, facilitate the circulation through 

 the heart muscle. The minimum manom- 

 eter fails to show a negative pressure in 

 the coronary arteries. The ventricle acts 

 on the coronary circulation as a force 

 pump, and not, to any noticeable extent, as 

 a suction pump. 



TJie Circidation through the Vessels of Thebesius. 

 W. T. PoETEE (for F. H. Peatt). 

 In nearly all experiments the freshly ex- 

 cised heart of the cat has been used. The 

 auricles are tied off from the ventricles, and 

 both coronary arteries ligated. A large 

 cannula is introduced into the right ventri- 

 cle through the pulmonary artery and 

 secured by a ligature. This cannula is 

 now supported vertically, so that the heart 

 shall hang from its lower end, and defibri- 

 nated blood poured in from the top, so as 

 to fill the ventricle and rise in the cannula 

 to a height of several inches. The ventri- 

 cle distends, and all the coronary veins be- 



come filled with blood ; the coronary ar- 

 teries remain empty. The ventricle begins 

 to contract rhythmically, slowly at first, 

 but gradually attaining the normal rate. 

 Suspending the heart in warm normal 

 saline solution facilitates the action. The 

 blood within the ventricle and in the veins 

 becomes venous, and, if contractions are to 

 be sustained, must periodically be renewed. 

 If a vein is opened, a small but steady out- 

 flow of blood occurs. Increasing the load 

 beyond that furnished by a blood column of 

 four or five inches lowers the force of con- 

 traction. Contractile activity may be kept 

 up by this method for some time. Eight 

 hours after excision is the maximum dura- 

 tion so far obtained, and in this case the 

 ventricle was still active when left. 



The experiments above described indi- 

 cate plainly a nutritive phenomenon ; the 

 blood becomes reduced, and must be re- 

 newed in order to sustain contraction. 

 That the contractions are not due to mere 

 mechanical stimulus is proved by the fact 

 that Ringer's solution fails to carry on the 

 process. A genuine circulation exists be- 

 tween the ventricular cavity and the coro- 

 nary veins through the vessels of Thebesius. 

 The possibility of a nutrition from the ven- 

 tricles direct may serve to explain some 

 cases in which thrombosis or other stop- 

 page of the coronary arteries has failed to 

 destroy the normal activity of the heart. 

 This method of nutrition bears a strong re- 

 semblance to that found in the frog. 

 Tlie Innervation of the Heart of the Opossum 



(Didelphys virginiana) . Reid Hunt (with 



D. W. Haeeington). Read by title. 



(1) Vagus. Standstill of the heart is 

 easily produced by stimulation of the peri- 

 pheral end of the vagus ; the duration of 

 the standstill is greater than that usually 

 observed in other mammals. The heart 

 beats slowly for some time after the cessa- 

 tion of the stimulus, i. e., there is a long 

 after-efi"ect. By continuous weak stimula- 



