THE INCUBATION OF HENS' ECCS 



181 



sixteen lidurs after fertili/atioii, \\lii<'li iisii:ill> (imls tlie e,ni;' 

 still within the body of the hen ( h'ii^nre N(i) 



" The ]>()siti()n of the iiiaiii enihryonie axis is fairl\ nnifui-ni, 

 tlidugli not coni])letely fixed. It lies a])]iroxiniately at ri^lit 

 aiiii'les to the long axis of the whole egg, the anterior end of 

 the enihryo direeted to the left when the sharp end of the egg 

 is held ])oiiiting away from the <)l)ser\er."' 



Via. S6 



Emljryi) cliick, sixteen liours oIJ. Maynificd. (Courtesy mI" luHa 

 A^^iicull iiial Experiment Station.) 



If, after laying, the teniperatnre of a fertile egg is allowed 

 to fall below a teniperatnre of (iS° F., all growth eeases, and 

 the egg remains in a dormant condition niitil its teniperatnre 

 is again raised to incuhating temperatures. ^\ hile de\elop- 

 ment takes place at all degrees of teniperatnre between 

 68° F. and that which is sufficiently high to destroy tlie life 



1 Kellicott, Chordate Development. 



