3 6o 



BIOLOGY AND ITS MAKERS 



vclop they become successively more and more complex, 

 and in their shifting history many rudimentary organs arise 



s 



: . 



1 



- 



*$! 



- - fv< - 



v ; " 



' " ' " 



FIG. 108. Fossil Remains of a Primitive Bird (Archeopteryx). 

 From the specimen in the Berlin Museum. (After Kayser.) 



and disappear. For illustration, in the young chick, devel- 

 oping within the hen's egg, there appear, after three or four 



