220 Mayow 



Let us also ponder briefly whether the gentle 

 warmth produced in the egg by the heat of the 

 incubating fowl does not contribute in some measure 

 to compensate for the want of respiration. For it 

 was elsewhere shown that nitro-aerial particles are 

 detached from the aerial particles by the fermentation 

 of the blood, and that these, in animals, serve the 

 purpose of respiration. Further, it ought to be 

 noted that heat of all kinds is produced by the 

 motion of nitro-aerial particles. 



But now as it is altogether needful for the genera- 

 tion of the chick that a gentle warmth be excited in 

 the Qgg^ by the heat of the incubating fowl or other- 

 wise, why should we not suppose that nitro-aerial 

 particles (from the copimunication of which to the 

 t,gg its warmth arises) supply to some extent the 

 place of respiration in the ^^^ ? Certainly the nature 

 of the white of egg seems to be such as is suitable 

 for the detention and entanglement of nitro-aerial 

 particles, inasmuch as it consists of a viscid fluid, and 

 that, too, impregnated with saline particles liberated 

 from union with sulphureous particles. It corro- 

 borates this view that the white of an Qgg^ if whipped 

 rapidly with a rod or spoon, becomes frothy more 

 than all other substances on account of the abundant 

 intermixture with it of aerial matter. It is therefore 

 probable that nitro-aerial particles, when conveyed to 

 the Qgg by the warmth of the incubating fowl, are 

 detained there by its albugineous humour ; and that 

 when at last collected by the almost innumerable 

 ramifications of the umbilical vessels and then 

 brought in great abundance to the foetus, they 

 compensate in some degree for the want of respiration 

 in the Qgg. For the chief use of the respiration 

 of animals is to introduce nitro-aerial particles 



