Movements of the Heart of the Copper-head Snake. 31 



to determine. This much may be stated generally, that it 

 will be the strong muscular contractions of the ventricular 

 walls which will produce the movement. The fibres there 

 are arranged spirally (at least in higher Mammals), and as 

 each spiral contraction drives the blood forward when the 

 heart is attached, so the force normally employed in doing 

 so is now expended in sending forward towards the base 

 the detached heart itself The short and sharp contraction 

 of the ventricle might be supposed to give a jerking action 

 to the progressive movement of the heart, and as a matter 

 of fact, in the frog's heart it was so ; but here, the heart 

 seemed to glide gently along, as if an intermittent source of 

 energy was converted into a continuous movement. 



There is likewise a deep interest attaching to such move- 

 ment, not only as showing the abounding vitalit}^ possessed 

 by the heart, even when out of the body, but as exhibiting 

 in a very appreciable form the force and direction of the 

 heart's energy. In the rabbit and kitten it is the same 

 direction, but in the frog it is mostly the opposite, or 

 apex-ward, and thus there is an important difference in the 

 behaviour of the excised Amphibian heart, as against the 

 Reptilian and Mammalian hearts. There is no occasion to 

 enter into a detailed explanation of this fact now, but it may 

 be noted in passing, that Drs. Waller and Reid* state in 

 connection with their electrical examination of the isolated 

 heart, "all our observations support the theory, that the 

 contraction proceeds from base to apex" in the frog, and 

 " that the contraction begins at the apex and ends at the 

 base of the ventricles " in the Mammals. 



Resuming the record of the beats, this was as a rule 

 taken every half-hour. The first half-hour after excision, 

 three successive minutes gave 34, 35, 35 respectively, the 

 beats being very regular and with vigorous stroke. The 

 second half-hour the beating was still regular, but weaker, 

 and 28 beats per minute for three minutes in succession 

 were recorded. Fifteen minutes afterwards, 21 and 20 beats 

 per minute were recorded. The third half-hour the beating 

 Avas still fairly regular, and ran for five minutes in succession 

 20, 23, 22, 23, 23 respectively. The fourth half-hour the 

 beating was steady, but feeble, and gave for 5 minutes in 

 succession 17, 15, 16, 16, 16 respectively. The fifth half- 

 hour showed very feeble beating, and a perceptible 



* Phil. Trans., 18H7, B. and Nature, Vol. xxxviii, 18S8. 



