76 Ornithology. 



Immediately under the shell, lies that common membrane or 

 skin, which lines it on the inside, adhering closely to it every 

 where, except at the broad end, where a little cavity is left, 

 that is filled wiih air ; which increases as the animal grows 

 larger. Under this membrane are contained two whites^ 

 though seeming to us to be only one; each wrapped up in a 

 membrane of its own, one white within the other. They differ 

 from each other in specific gravity. In the midst of all is 

 the yolk, wrapt round likewise with its own membrane. At 

 each end of this are two ligaments, called chalazcB, which are 

 white, dense substances, made from the membranes, and ser- 

 ving to keep the white and the yolk in their places. They 

 are called chalazae from their resemblance to hail. 



The cicatricula is the part where the animal first begins 

 to show signs of life ; it resembles a vetch or small pea lying 

 on one side of the yolk and within its membranes. The 

 outer membranes and ligaments preserve the fluids in their 

 proper places, the white serves as nourishment ; and the yolk 

 with its membranes after a time, becomes a part of the bird's 

 body. 



The growth of an egg after impregnation is exceedingly 

 rapid ; the yolk only is formed in the ovarium,, where it re- 

 mains till within twenty-four hours of being produced ; when 

 that part is fully matured, it separates and falls down the 

 oviduct into the uterus, where the egg is perfectly formed ; 

 first the vitellus or yolk is surrounded by the albumen or white; 

 and lastly is covered with a calcareous shell. The very ex- 

 peditious growth of these last, appear to be an extraordinary 

 exertion of nature. The calcareous covering of an egg is 

 concreted and formed in a most expeditious manner; a few 

 hours only seem necessary for this work. Only one vitellus 

 separates from the ovarium at a time, (except as we shall 

 hereafter mention,) till the exclusion of which no other suc- 

 ceeds. But as this is a daily production, with few exceptions, 

 there is no more time allowed for perfecting the albumen 

 and shell than twenty-four hours. 



As the course of nature is obstructed by remote causes, 

 there are few general rules without some exceptions ; but 

 an individual deviation by no means perverts the law of 

 nature, but is simply an individual defect. We shall here 

 instance imperfect eggs sometimes produced, such as want 

 the vitellus,^ and others containing two yolks ; and although 



* The centininum Ovum of naturalists, vulgarly called a cock's egg. 

 This name has been given to it from a supposition that it was the 100th 

 egg, or the last the bird could lay. 



^'iv 



