270 



ELEMENTS OF GENERAL SCIENCE 



embryo by examining eggs in various stages of incubation. 

 It will be seen that at first the small embryo is reddish in 

 color and that radiating lines of blood vessels extend from 

 it into tin- Idod material. The developing embryo soon differ- 

 entiates bone, mus- 

 cle, nerve, and other 

 tissues. In a short 

 time the organs that 

 are recognized in 

 the adult bird may 

 l)e found completely 

 differentiated in the 

 embryo that is still 

 retained within the 

 egg wall. It is ap- 

 parent, therefore, 

 that a development 

 of the embryo within 

 the egg cell has many 

 features in common 

 with the develop- 

 ment of the frog, 

 as already noted. 

 In the higher 

 animals, known as 

 mammals, and in 

 some others, the 

 egg develops into 



the young animal 

 The sepals and petals are almost identical in shape and * vi i^ 



color. There are six stamens and one pistil while Still Wltnin 



the body of the 



mother. In the reproduction of these animals the new individ- 

 uals are born with their various structures already well formed. 

 303. Reproduction in seed plants : the flower. Reproduction 

 in seed plants is in some respects quite similar and in others 



FIG. 128. Flower of amaryllis 



