1 82 DIVERSIONS OF A NATURALIST 



several) individuals thus melt together and become one 

 individual — a process the exact reverse of the division of 

 one into two. This is known to microscopists as " con- 

 jugation." The new individual resulting from conjugation 

 after a time divides, and the individuals thus produced, 

 each consisting of a mixture of the fused and thoroughly 

 mixed substance of the two conjugated individuals, feed 

 and grow and divide in their turn, and so on for several 

 generations, until again the epidemic of conjugation sets 

 in, and the scattered offspring of many distinct pairs of 

 the previous conjugation-season in their turn conjugate. 



It is clear that the tendency of this process is to 

 prevent the continued multiplication of one stock or line 

 of descent in a pure state. By conjugation different lines 

 of descent — the progeny of different individuals, often 

 brought together from widely separate localities — are 

 blended and fused. And this is, we are led to conclude, 

 a matter of immense importance. To effect this mixture 

 of separate stocks is, as Darwin has shown, a prime 

 purpose of the habits and structures implanted in the 

 very substance of living things, and developed ' and 

 accentuated in endless ways and with extraordinary 

 elaboration of mechanisms and procedure during the 

 immense lapse of ages during which life has unfolded 

 and developed on this earth. The fusion of different 

 strains by conjugation gives increased variation in the 

 offspring or new generations : for the two parental strains 

 differ more or less, as all living individuals do, from one 

 another. The result of their fusion is different from 

 either parent. In fact, the process of fusion itself causes 

 a disturbance — a readjustment of the living matter — so 

 that completely new variations result and are selected or 

 rejected in the struggle for existence. Either parental 

 strain was perhaps not so suitable to a newly developed 



