Multiplication of Extremes 749 



life. Afterwards only the minor points remain 

 to be regulated. This makes it at once clear 

 that the range of individual and partial vari- 

 ability together must be wider than that of 

 either of them, taken alone. Partial fluctua- 

 tions cannot, of course, be excluded. Thus our 

 comparison is limited to individual and partial 

 variability on one side, and partial fluctuations 

 alone on the other side. 



Intra-specific selection is thus seen to fall 

 under two heads: a selection between the in- 

 dividuals, and a choice within each of them. 

 The first affords a wider and the latter a nar- 

 rower field. 



Individual variability, considered as the re- 

 sult of outward influences operative during ex- 

 treme youth, can be excluded in a very simple 

 manner. Obviously it suffices to exclude ex- 

 treme youth, in other words, to exclude the use 

 of seeds. Multiplication in a vegetative way, 

 by grafting and budding, by runners or roots, 

 or by simple division of rootstocks and bulbs is 

 the way in which to limit variability to the par- 

 tial half. This is all we may hope to attain, but 

 experience shows that it is a very efficient means 

 of limitation. Partial fluctuations are gener- 

 ally far smaller than individual and partial 

 fluctuations together. 



Individual variability in the vegetable king- 



