96 WILLIAM HARVEY 





those animals that have, as it were, no more than a s 

 ventricle to the heart, such as toads, frogs, serpents, and 

 lizards, which have lungs in a certain sense, as they have 

 a voice. I have many observations by me on the admirable 

 Itructure of the lungs of these animals, and matters apper- 

 taining, which, however, I cannot introduce in this place. 

 Their anatomy plainly shows us that the blood is trans- 

 ferred in them from the veins to the arteries in the same 

 manner as in higher animals, viz., by the action of the heart ; 

 the way, in fact, is patent, open, manifest; there is no 

 difficulty, no room for doubt about it; for in them the mat- 

 ter stands precisely as it would in man were the septum of 

 his heart perforated or removed, or one ventricle made out 

 of two; and this being the case, I imagine that no one will 

 doubt as to the way by which the blood may pass from the 

 veins into the arteries. 



But as there are actually more animals which have no 

 lungs than there are furnished with them, and in like man- 

 ner a greater number which have only one ventricle than 

 there are with two, it is open to us to conclude, judging from 

 the mass or multitude of living creatures, that for the major 

 part, and generally, there is an open way by which the 

 blood is transmitted from the veins through the sinuses or 

 cavities of the heart into the arteries. 



I have, however, cogitating with myself, seen further, 

 that the same thing obtained most obviously in the embryos 

 of those animals that have lungs; for in the foetus the four 

 vessels belonging to the heart, viz., the vena cava, the pul- 

 monary artery, the pulmonary vein, and the great artery 

 or aorta, are all connected otherwise than in the adult, a 

 fact sufficiently known to every anatomist. The first con- 

 tact and union of the vena cava with the pulmonary veins, 

 which occurs before the cava opens properly into the right 

 ventricle of the heart, or gives off the coronary vein, a 

 little above its escape from the liver, is by a lateral anasto- 

 mosis; this is an ample foramen, of an oval form, com- 

 municating between the cava and the pulmonary vein, so 

 that the blood is free to flow in the greatest abundance by 

 that foramen from the vena cava into the pulmonary vein, 

 and left auricle, and from thence into the left ventricle. 





