HEREDITY AND VARIATION 



207 



Fig. 118. — The narrow hereditary bridge. The plant at the right receives 

 from each of its parents only one minute sexual cell, a male gamete from one and 

 a female gamete from the other. The parents, in turn, receive from each of the 

 grandparents but one sexual cell. Thus the bridge which connects one generation 

 with the next, and over which the entire inheritance must pass, is an exceedingly 

 narrow one. The actual gametes are very much smaller, both actually and in pro- 

 portion to the size of the plant, than the dots by which they are here represented. 



