396 OF THJB DIFFERENCES IN THE SYSTEM 



appears as adolescence proceeds, but, in the foetus, 

 appears to direct* the stream of blood coming from 

 the abdomen towards an opening, immediately to be 

 mentioned, existing in the septum of the auricles. 



628. This opening is denominated the foramen ovale, f 

 and is the cause that certainly the greatest part of the 

 blood which streams from the inferior cava is poured 

 into the left auricle during the diastole of the auricles. 

 A falciform J valve, placed over the foramen, prevents 

 its return, and appears likewise to preclude its course 

 into the left auricle during the systole of the auricles. 

 By means of this valve, the foramen generally becomes 

 closed in early infancy in proportion as the correspond- 

 ing Eustachian valve decreases and more or less com- 

 pletely disappears. § 



629. The blood which enters the right auricle and 

 ventricle principally proceeds from the superior cava, 

 and flows but in a very small quantity into the lungs, 

 while, from the right ventricle, which, in the foetus, is 

 particularly thick and strong for this purpose, it pur- 

 sues its course directly to the arch of the aorta, by 

 means of the ductus arteriosus, || which is in a manner 

 the chief branch of the pulmonary artery. A few weeks 



» J. F. Lobstein, De valvula Etutackii. Arg. 1771. 4to. 

 f Haller,- De foramine ornli et Etutachii valvula. dotting. 1748. fol. 

 c. f. ae. and much more copiously in his Opera minora. T. i. p. 33 sqq. 



X For an account of the opinion of C. Fr. Wolff, who regards the foramen 

 ovale as another mouth of the inferior cava, opening into the left auricle in the 

 same manner as the mouth commonly known opens into the right, See Nov. 

 Comment. Acad. Scient. Petropol. T. XX. 1775. 



§ H. Palm. Leveling, De valvula Eustachii et foramine ovali. Anglipol. 

 1780. 8vo. c. f. ae. 

 II B. S. Albinus, .{nnot. acad. L. ii. tab. vii. tig. 7. 



