16 THE COMPLETE POULTRY BOOK. 



"The way in which these atoms build themselves togeiher is to me perfectly 

 astonishing. You have here a play of power as wonderful as vitality itself. And 

 depend upon it, trust me, the revelations of science are not in the least degree 

 calculated to lessen our feelings of astonishment. We are surrounded by won- 

 ders and mysteries everywhere. I have sometimes — not sometimes, but often — 

 in the spring-tide— watched the advance of the sprouting leaves, and of the grass 

 and of the flowers, and observed the genial joy of opening life in nature, and I 

 have asked myself this question : ' Can it be that there is no being nor thing in 

 nature that knows more about these things than I do? Do I in my ignorance • 

 represent the highest knowledge of these things existing in the universe?' The 

 man who puts that question to himself^ — if he be not a shallow man, if he be a 

 man capable of being penetrated by. profound thought — ^will never answer by 

 professing. tbe creed of atheism, which has been so lightly attributed to me." 



As the yelks pass throJigh the lower portions of the generative passages the 

 " white of egg," which is pure albumen and water, is deposited around them 

 in layers, the outermost of which is surrounded by two fibrous membranes, the 

 "shell membranes." These membranes adhere closely together throughout most 

 of their extent, but at the larger end of the egg they separate so as to form a small 

 vesicle, the "air bladder." Outside of these membranes is formed the shell, 

 which is a consolidated layer of the carbonate of lime, the same substance that ex- 

 ists in other forms as marble, chalk, etc. This layer is deposited in such a manner 

 as to give the greatest possible strength for the material used, and at the same 

 time is so arranged as to leave numerous pores, or breathing places, through 

 which the water of the egg may evaporate, and the external air penetrate to sup- 

 port the resjuration of the growing chick, or to set up the processes of decay by 

 which eggs are so soon addled when -exposed to the action of the atmosphere. 



When the egg is subjected to a continuous heat of a little more than one hun- 

 dred degrees, the germ, if it has been fertilized, soon begins to increase in size, 

 and within twenty-four hours small blood-vessels may be seen forming a beautiful 

 zone around it. If the heat be maintained, with proper conditions of moisture, 

 these blood-vessels will continue to extend, until by the third day they will have, 

 commenced the formation of a temporary membrane, lining the shell membranes 

 and called the aUcmtoiS, which gives rise to that opacity shown in fertile eggs 

 that have been sat upon. This membrane serves as the lungs of the growing 

 embryo, which absorbs the contents of the egg and converts them into blood, 

 which is aerated by exposure in the vessels of the allantois to the oxygen of the 

 ail that penetrates through the poies of the shell. This work goes on more and 

 more actively until the nineteenth day of incubation, by which time the lungs 

 of the embryo chick will have so far developed that they begin to ^rform their 

 proper function, and its beak will have ruptured the air vesicles at the large 

 end of the egg, which has considerably increased in size through the evaporation 

 of the water from the albumen of the egg. At this time a peculiar tapping-like 

 sound may be heard by placing the egg to the ear; this has been commonly 

 ascribed to the pecking ot the chick against the shell of the egg, but it has been 

 shown to be due to the respiratory action of the lungs of the young chick.* 

 About the end of the twenty-first day of incubation — a few hours s ooner with 



*Tegeti»elOT, 



