DEVELOPMENT. 64 i 



the egg are converted into the blood and differ- 

 ent organs of the chick, whether they be absorbed 

 through the pores of the shell during the process 

 of incubation or not ; and that as the germ of 

 viviparous animals is formed from an albuminous 

 secretion, before any connexion is established 

 with the circulation of the mother by means of 

 the placenta, it can receive no oxygen from the 

 maternal blood ; consequently, that it must be 

 developed by means of the same life-giving ele- 

 ment (Zwr^opov ITvp) that actuates the universe, 

 and fills it with beautiful creations : that causes 

 the germination of plants, the circulation of sap, 

 and its conversion into the various constituents 

 of their substance while passing through the 

 leaves, (where oxygen is not absorbed but given 

 off;) and by which the Egyptians annually pro- 

 duce one hundred millions of poultry from one 

 hundred and fifty millions of eggs, placed in a 

 few large ovens. Should it still be urged that 

 oxygen is indispensable to animal life, I answer, 

 so is it to the movements of the steam engine, 

 because by its chemical union with carbon and 

 hydrogen in the furnace, as in the lungs, the 

 moving principle is evolved ; and, because like 

 carbon, hydrogen, and nitrogen, oxygen is an es- 

 sential constituent of animal bodies. 



During the passage of dark venous blood 

 through the lungs in combination with chyle and 

 lymph, received from the thoracic duct, its tem- 

 perature is elevated, its colour changed to a bright 



