198 Mifcelhnea Cur to fa. 



I expect to be told, that m the early Days 

 of Geflation in Vivtparous\Amma\s, there is no ? la- 

 vent a, or any Adhefion of the Vmbilical Vef- 

 fels to any part of the Mother, and confequent- 

 ly no fuch Transfujion ; and that in Oviparous 

 there is no continuity, or communication of Vefc 

 fels of any kind, during the whole time of I»- 

 cubation. 



But thefe Objections carry neither the Weight 

 nor Difficulty along with them, that they may 

 be fuppos'd to do 5 for in thofe Days there 

 is neither Blood or Blood-Vejfels, and confequent- 

 ly there can be no Circulation of the Blood ; 

 and the Embryo, of what Species foever, is no 

 more than a Vegetable at that time \ nor does 

 the Foetus of any Viviparous Creature enjoy 

 any Circulation, or (hew any figns of Ani- 

 mal Life, till after thofe VefTels, as well as 

 others requisite to the Circulation, are com- 

 * pleated. 



It muft be confefs'd, that Oviparous Animals 

 are denied the benefit of this Communication ; 

 but that want is (ufficiently compenfated by a 

 peculiar Mechanifin, which dire&ly anfwers the 

 ends of fyfpiration, and the prejfure of the At* 

 mofpere upon the Foetus* There is at the ob» 

 tuje end of an Egg a fmall Cavity fill'd with 

 Air, which is the liiccedaneous Inftrument to 

 the Hefpiratory Organs. For as foon as the 

 Contents begin to be warm'd by the Incubation 

 of the Hen, or any analogous Heat of Furnace or 

 )Ounghil, the fever al Humours of the Egg re- 

 quire a fermentative motion, and the Air con- 

 tain d in the Cavity or Vejicle , at the obtufe end 

 of the Egg, is rarefied, and the Veficle extended 

 and enlarg'd, and confequently the other Con- 

 tents 



