238 ON GENERATION. 



punctum saliens when all but dead, and no longer giving any 

 signs of motion, recover its pulsatile movements under the in- 

 fluence of renewed warmth. In the order of generation, then, 

 I conceive that the punctum and the blood first exist, and that 

 pulsation only occurs subsequently. 



This at all events is certain, that nothing whatever of the 

 future foetus is apparent on this day, save and except certain 

 sanguineous lines, the punctum saliens, and those veins that all 

 present themselves as emanating from a single trunk, (as this 

 itself proceeds from the punctum saliens,) and are distributed in 

 numerous branches over the whole of the colliquament or dis- 

 solved fluid. These vessels afterwards constitute the umbilical 

 vessels, by means of which, distributed far and wide, the foetus 

 as it grows obtains its nourishment from the albumen and vi- 

 tellus. You have a striking example of similar vessels and their 

 branchings in the leaves of trees, the whole of the veins of which 

 arise from the peduncle or foot-stalk, and from a single trunk 

 are distributed to the rest of the leaf. 



The entire including membrane of the colliquament traversed 

 by blood-vessels, corresponds in form and dimensions with the 

 two wings of a moth; and this, in fact, is the membrane which 

 Aristotle 1 describes as "possessing sanguineous fibres, and at 

 the same time containing a limpid fluid, proceeding from those 

 mouths of the veins/' 



Towards the end of the fourth day, and the beginning of the 

 fifth, the blood-red point, increased into a small and most deli- 

 cate vesicle, is perceived to contain blood in its interior, which 

 it propels by its contractions, and receives anew during its 

 diastoles. 



Up to this point I have not been able to perceive any differ- 

 ence in the vessels : the arteries are not distinguished from the 

 veins, either by their coats or their pulsations. I am therefore 

 of opinion, that all the vessels may be spoken of indifferently 

 under the name of veins, or, adopting Aristotle's 2 term, of venous 

 canals. 



" The punctum saliens," says Aristotle, " is already possessed 

 of spontaneous motion, like an animal." Because an animal 

 is distinguished from that which is none, by the possession of 



1 Loc. supra cit. * Ib. 



