2 22 Mayow 



after respiration once begins, is taken round by an 

 entirely new path through the lungs, and that it 

 cannot be transmitted through them without their 

 continuous movement. For I think it is clear from 

 what has been said that this answer fails to remove 

 the difficulty. It should rather be said, I think, that 

 the albugineous juice contained in the placenta, or in 

 the membranes in which the foetus is enclosed, have 

 a supply of nitro-aerial particles large enough to 

 continue for a time the respiration and the life of the 

 infant. Indeed, the foetus when born and wrapped in 

 its unruptured membranes, seems to be in nearly the 

 same case and to breathe very much in the same way 

 as the chick enclosed in the Qgg. If, however, the 

 foetus is stripped of its, membranes, and contracts the 

 muscles of the chest and the diaphragm that respira- 

 tion may begin — certainly no small exertion — there is 

 now a greater expenditure of nitro-aerial particles for 

 muscular effort, and consequently the foetus is under 

 a greater necessity to breathe, since nothing is any 

 longer received to supply the want of respiration. 



It will not be irrelevant to inquire here whether 

 the air which is contained in the cavity in the blunter 

 end of every q^^^ contributes to the respiration of 

 the chick. This cavity lies between two membranes 

 which are stretched over the whole interior of the 

 Qgg. For of these membranes, the one which is next 

 the shell is in all parts firmly attached to it, but the 

 other, which is next the fluids of the ^gg^ adheres 

 almost everywhere to the first, except that by reced- 

 ing from it a little at the blunt end of the Qgg^ it 

 forms the aforesaid cavity there. Harvey and others 

 have supposed that this cavity lies between the 

 membrane which envelops the fluids and the shell, 

 which is left bare at that place by the other 



