306 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
only A and a can pair together, B and 6, and C and c, but each pair 
operates independently of the other so that in the ensuing reduction 
division either member of a pair may get into a cell with either member 
of the other pairs. That is, the line up for division at a given reduc- 
tion might be any one of the following, 
—— re sere This would yield the following eight kinds of 
gametes, ABC, abc, ABc, abC, Abc, aBC, AbC, aBc, each bearing one 
of each kind of chromosome required to cover the entire field of 
characters necessary to a complete organism. And since each sex 
would be equally likely to have these eight types of gametes and any 
one of the eight in one individual might meet any one of the eight of 
the other, the possible number of combinations in the production of a 
new individual from such germ-cells would be 8X8, or 64. With 
the larger numbers of chromosomes which exist in most animals it is 
readily seen that the number of possible combinations becomes very 
great. Thus any individual of a species with twenty chromosomes 
—and many animals, including man, have more—would have ten 
pairs at the reduction period and could therefore form (2), or 1,024 
different gametes in each sex. And since any one of these in one 
sex would have an equal chance of meeting with any one in the oppo- 
site sex, the total number of possible different zygotes that might be 
produced would be (1,024)?, or 1,048,576. Sex, therefore, through 
recombinations of ancestral materials, undoubtedly means, among 
other things, the production of great diversity in offspring. 
