464 The Bird 



vorticella, on their queer Uttle corkscrew stems. All these 

 are made up of but a single cell, and in the beginning all 

 seeds of plants and all eggs of animals likewise consist of 

 one cell. 



If we examine a chicken while it is being dressed for the 

 table, we can easily find the ovary, a mass of hundreds 

 of tiny golden spheres, — eggs which would have been 

 laid during the coming years. So we realize that the most 

 essential part, in fact the real egg, is only the yolk; all 

 else being merely protective. The shell protects the yolk 

 while the chick is developing during incubation, and 

 although formed of crystals of lime, yet it is so porous 

 that oxygen can enter and carbonic acid gas escape. The 

 viscid white, or albumen, is nutritious as well as protective, 

 while the yolk itself is the real food of the embr3^o and also 

 acts as a support to the developing chick. If we look 

 carefully, we will see two whitish, twisted strands which 

 extend from the yolk through the white. These two strands 

 have whitish opaque knots strung along them, and from a 

 fancied resemblance to hailstones they are called chalazce. 

 These act as pads to protect the yolk from sudden jars, 

 but the}^ do not act as suspensories. A hen never turns 

 her eggs, as many people imagine, to warm the different 

 sides equally, for the germ-dot — the position of the future 

 embryo (of which we will speak presently) — is always 

 on the lightest side of the yolk, and whichever way the egg 

 is turned it always swings uppermost, nearest the heat 

 from the body of the sitting hen. The turning, however, 

 may be of advantage in allowing moisture to act upon a 

 greater surface of shell. 



