CHAPTER XVII 



THE BIRD IN THE EGG 



HE embryology, or life of the bird in the egg, is 

 the most mysterious and wonderful part of the 

 entire physical aspect. Many of the lesser de- 

 tails of growth are yery difficult to study without the 

 use of microscopic sections and wax models; but a little 

 knowledge of the subject is more interesting and simple 

 than one would imagine. 



The very best way to begin our study of the life in the 

 egg will be to go to the nearest pond or marsh, if it is spring- 

 time, and bring home a pailful of freshly laid frog's eggs 

 — those queer, gelatinous masses filled with black dots. 

 Place them in a flat, white basin, and into a smaller saucer 

 near by break a fresh hen's egg, being careful not to injure 

 the yolk. Separate one of the frog's eggs with a spoon 

 and put it beside that of the fowl. Now examine them 

 carefully with a good dissecting-microscope or eyen with 

 a hand-lens. 



We see a large, round, yellow yolk in the case of one 



egg, and a tiny speck of black and white in the other, — 



both apparently inanimate bits of matter, but which, 



merely by the application of heat in the one instance 



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