166 HEREDITY AND ENVIRONMENT 



alone, and when the cards are dealt into two 

 hands as before one hand will contain 24 cards 

 and the other 23. 



If now we complete this comparison by ex- 

 tending it to what takes place in fertilization 

 we must take one hand from each of these 

 deals and put them together into one pack; 

 this pack would contain cards of every de- 

 nomination from ace to queen but there would 

 be varying numbers of red and black cards and 

 a mixture of cards from two distinct packs. 

 In no game of cards do corresponding cards 

 from different packs have slightly different 

 values nor are half of the cards taken from one 

 pack and half from another at every game, but 

 this is just what happens in the shuffle and 

 deal of the chromosomes. Because of the mix- 

 ture of chromosomes from distinct individuals 

 in every generation, each of which has its own 

 peculiar value, the game of heredity becomes 

 vastly more complex than any game of cards. 



This illustration may serve to make plain 

 the fact that in the process of maturation and 

 fertilization there is this shuffle and deal of 

 the chromosomes, with the result that every 



