Multiplication of Extremes 745 



selection-process. In practice it is of secondary 

 importance, and in nature it takes a very subor- 

 dinate position. For this reason it will be best 

 to confine further discussions to the experience 

 of the breeders. 



Two different ways are open to make fluctuat- 

 ing variability profitable. Both consist in the 

 multiplication of the chosen extremes, and this 

 increase may be attained in a vegetative man- 

 ner, or by the use of seeds. Asexual and sexual 

 propagation are different in many respects, and 

 so they are also in the domain of variability. 



In order to obtain a clear comprehension of 

 this difference, it is necessary to start from the 

 distinction between individual and partial fluc- 

 tuations, as given in the last lecture. This 

 distinction may be discussed more understand- 

 ingly if the causes of the variability are taken 

 into consideration. "We have dealt with them\ 

 at some length, and are now aware that inner | 

 conditions only, determine averages, while some / 

 fluctuation around them is allowable, as influ-/ 

 enced by external conditions. These outward 

 influences act throughout life. At the very first 

 they impress their stamp on the whole organism, 

 and incite a lasting change in distinct directions. 

 This is the period of the development of the 

 germ within the seed ; it begins with the fusion 

 of the sexual cells, and each of them may be in- 



