THE ORIGIN AND DEVELOPMENT OF ORGANISMS 337 



method is continued the plants remain essentially constant. 

 If, however, he wishes to obtain new types, he adopts the 

 method of planting the seeds. Seeds, as we have seen, come 

 from the sex process of reproduction, and the offspring which 

 come from seeds show a far greater tendency to variability 

 than those which come from buds by the asexual process. It 

 is the general conclusion from observation that variations are 

 more common among organisms multiplying by the sexual 

 process. With this understanding, one purpose and function 

 of the union of the sex cells becomes intelligible. 



DIVERGENCE FROM TYPE 



The term "divergence from type" is the exact opposite of 

 the term "conformity to type." It is no less evident that 

 animals and plants tend to diverge from the race type than it 

 is that they conform to type. The reconciliation of these two 

 contradictory facts is that though, in general, successive gen- 

 erations conform to the type of the race, the individuals show 

 more or less variation from each other, and, moreover, the 

 whole race is slowly changing, so that the type itself in time 

 undergoes modifications. 



Individual Variations. An infinite number of slight differ- 

 ences are found between individuals of the same species. This 

 fact is clear to everyone who is at all familiar with animals. 

 In the human race, it is well recognized that no two individuals 

 are exactly alike, and the same thing is equally true among all 

 species of animals and plants. The different individuals of 

 the same species differ in size, color, habits, and in an infinite 

 number of minor points, like the length of legs, the length of 

 hair, the size and shape of leaves, flowers, etc. Indeed, there 

 is no part of an animal or plant that does not show more or 

 less of such variation. It is so evident that it needs no further 

 discussion. While the different individuals conform to the 

 type of their species in general character, in numerous details 

 they differ from each other in almost endless fashion. 



