REPRODUCTION IN PLANTS AND ANIMALS 367 



formed in the body of the female and expelled into the 

 water when mature. At the same time that the female lays 

 the eggs, the male frog expels from his body into the water 



FIG. 170. Development of the frog 



A, eggs; B and C, early stages of the embryo; D, tadpole as commonly seen; 



E and F, legs appearing ; G and H, front legs appearing and tail disappearing ; 



/, mature frog. B and C are enlarged much more than the other parts of the 



illustration, the others being approximately natural size 



a whitish fluid which is shown by the microscope to contain 

 great numbers of very minute cells, known as sperms. The 

 sperms swim about actively in the water and come in contact 



