44 Motion of the 



the arteria venalis or pulmonary vein, and the arteria 

 magna or aorta, are all connected otherwise than in the 

 -adult ; a fact sufficiently known to every anatomist. 

 The first contact and union of the vena cava with the 

 -arteria venosa or 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 anastomosis ; this 

 is an ample foramen, of an oval form, communicating 

 between the cava and the arteria venosa, or pulmonary 

 vein, so that the blood is free to flow in the greatest 

 .abundance by that foramen from the vena cava into the 

 arteria venosa or pulmonary vein, and left auricle, and 

 from thence into the left ventricle ; and farther, in this 

 foramen ovale, from that part which regards the arteria 

 venosa, or pulmonary vein, there is a thin tough 

 membrane, larger than the opening, extended like an 

 operculum or cover ; this membrane in the adult 

 blocking up the foramen, and adhering on all sides, 

 Anally closes it up, and almost obliterates every trace 

 of it. This membrane, however, is so contrived in the 

 foetus, that falling loosely upon itself, it permits a ready 

 .access to the lungs and heart, yielding a passage to the 

 Wood which is streaming from the cava, and hindering 

 the tide at the same time from flowing back into that 

 vein. All things, in short, permit us to believe that in 

 the embryo the blood must constantly pass by this 

 foramen from the vena cava into the arteria venosa, or 

 pulmonary vein, and from thence into the left auricle 

 of the heart ; and having once entered there, it can 

 snever regurgitate. 



Another union is that by the vena arteriosa, or 

 pulmonary artery, and is effected when that vessel 

 'divides into two branches after its escape from the 

 eight ventricle of the heart. It is as if to the two 

 trunks already mentioned a third was superadded, a 

 kind of arterial canal, carried obliquely from the vena 

 .arteriosa, or pulmonary artery, to perforate and termi- 



