DIFFERENTSYSTEMS. 103 



veflels, which are of a dark colour. 1038 hours, 

 the chick has acquired more ftrength; its head 

 is very large, and three veficles appear in it fur- 

 rounded with membranes, which likewife in- 

 clude the fpine of the- back ; through which, ' 

 however, the vertebrae are ftill vlfible. At the 

 end of 40 hours, it was admirable to oblerve, 

 continues our author, the chick living in the 

 centre of the liquor of the amnios. The back- 

 bone was increafed, the head was bended, the 

 veficles of the brain were lefs bare, the rudi- 

 ments of the eyes appeared, the heart beat, and 

 the blood circulated. Here Malpighius defcribes 

 veffels and the circulation of the blood ; and he 

 thought, with reafon, that, though the heart did 

 not beat till 38 or 40 hours after incubationwas 

 begun, it nevertheleis exifted before, as well as 

 the other parts of the chick. But, on exami- 

 ning the heart in a dark chamber, he obferved 

 nothing like luminous fparks iifuing from it, as 

 Harvey feems to infinuate. 



At the end of the fecond day, the foetus ap- 

 peared fwimming in the liquor of the amnios. 

 The head, which Teemed to be compofed of ve- 

 ficles, was bended ; the back-bone and verte- 

 brae were lengthened j the heart, which hung 

 out of the breaft, beat three times fucceffively, 

 becaufe the fluid it contains is puflied from the 

 auricle into the ventricles, from the ventricles 

 into the arteries, and, laflly, into the umbilical 

 VcfTcls. He remarks, that, having fcparatcd the* 



chick 



