38 MOTION OF THE 



be said in regard to the assertion that the heart in the embryo 

 does not pulsate, that it neither acts nor moves, so that nature 

 was forced to make these communications for the nutrition of 

 the lungs. This is plainly false ; for simple inspection of the 

 incubated egg, and of embryos just taken out of the uterus, shows 

 that the heart moves precisely in them as in adults, and that 

 nature feels no such necessity. I have myself repeatedly seen 

 these motions, and Aristotle is likewise witness of their reality. 

 " The pulse," he observes, " inheres in the very constitution of 

 the heart, and appears from the beginning, as is learned both 

 from the dissection of living animals, and the formation of the 

 chick in the egg." 1 But we further observe, that the passages 

 in question are not only pervious up to the period of birth in 

 man, as well as in other animals, as anatomists in general have 

 described them, but for several months subsequently, in some 

 indeed for several years, not to say for the whole course of 

 life ; as, for example, in the goose, snipe, and various birds, 

 and many of the smaller animals. And this circumstance it 

 was, perhaps, that imposed upon Botallus, who thought he had 

 discovered a new passage for the blood from the vena cava into 

 the left ventricle of the heart ; and I own that when I met with 

 the same arrangement in one of the larger members of the 

 mouse family, in the adult state, I was myself at first led to 

 something of a like conclusion. 



From this it will be understood that in the human embryo, 

 and in the embryos of animals in which the communications are 

 not closed, the same thing happens, namely, that the heart by 

 its motion propels the blood by obvious and open passages from 

 the vena cava into the aorta through the cavities of both the 

 ventricles ; the right one receiving the blood from the auricle, 

 and propelling it by the vena arteriosa, or pulmonary artery, and 

 its continuation, named the ductus arteriosus, into the aorta; 

 the left, in like manner, charged by the contraction of its auricle, 

 which has received its supply through the foramen ovale from 

 the vena cava, contracting, and projecting the blood through 

 the root of the aorta into the trunk of that vessel. 



In embryos, consequently, whilst the lungs are yet in a state 

 of inaction, performing no function, subject to no motion any 



1 Lib. de Spiritu, cap. v. 



