bladder included in the membranous sac of the hen's 

 ovary .... When it reaches the size of the yolk . . 

 it (the bladder) destroys the membranes surrounding 

 it in the ovary. At the same time the included animal 

 or the primary bladder bursts, leaving on the surface 

 of the yolk, under the membrane, its enveloping white 

 speck or paunch, designating the place where the embryo 

 begins its development. The egg, containing in itself 

 the life conditions of the future chicken, can stay 

 for some time unchanged; . . . for the development of 

 life in the egg only warmth is necessary .... If 

 you put the fertilized egg under a brood hen, or in 

 a warm place, significant changes constantly take 

 place. In the first day, in the middle of the 

 elongated paunch, between both membranes of the yolk, 

 a whitish streak is observed with thickenings at the 

 ends and surrounded by a membranous fold .... This 

 streak is the rudiment of the head, the spinal brain, 

 from which develops all the brain and sensation 

 apparatus .... On succeeding days the one-cavity 

 heart appears separate from the brain apparatus . Soon 

 the left auricle forms, after which the auricle is 

 divided by a ring of membrane into two cavities . 

 After three days, the right ventricle becomes clear, 

 but the heart beats before its complete formation and 

 contains at that time uncolored fluid. The red blood 

 appears primarily in the vessels which form at a 

 distance from the embryo in the membranes of the yolk? 

 these vessels spread, become entangled, and push the 

 blood to the heart. Soon after the appearance of the 

 head and spinal brain, some pairs of spots appear 

 close to it, representing the vertebrae .... 

 After the appearance of the head, all the other 

 external parts of the chicken gradually form. But 

 that part of the abdomen which at the beginning is 

 entirely opened, gradually shrinks, so that by the 

 twentieth day it is absorbed by the remaining fluid 

 and becomes entirely closed." (pp. 157 - 158) 



"The development of the child takes place in a manner 

 similar to, but not identical with, the development of the 

 chick," Yakushkin added, giving the features of development 

 in the human embryo. "And thus," he continued, "observations 



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