10 



HEREDITY AND SEX 



He concludes that conjugation is not in itself bene- 

 ficial to all conjugants, but that the essence of the pro- 

 cess is that a recombination of the hereditary traits 

 occurs as shown in the diagram, Fig. 3 and 4. Some 



Fig. 4. — Illustrating conjugation between two stocks, with pairs of 

 factors A, B, C, D, and a, b, c, d ; and union of pairs into Aa, Bb, Cc, Dd. 

 After these separate, their possible recombinations are shown in the 16 

 smaller circles. (After Wilson.) 



of these new combinations are beneficial for special 

 conditions — others not. The offspring of those con- 

 jugants that have made favorable combinations will 

 soon crowd out the descendants of other conjugants 

 that have made mediocre or injurious combinations. 

 Hence, in a mass culture containing at all times large 



