262 THE EVOLUTION THEORY 



which transform the plant in accordance with the indirect influences 

 of new conditions of Hfe, cannot be brought about without a persistent 

 mingling of germ-plasms, simple modifications may readily appear 

 although amphimixis is altogether absent. If a wild plant be 

 permanently transferred to a well-manured culture-bed, it is probable 

 that certain changes will occur in it, either gradually or at once. 

 But these are not adaptations ; they are, so to speak, direct reactions 

 of the organism which do not even require selection to make them 

 increase, but depend upon the influencing of certain determinants 

 of the germ-plasm, and which, like all germinal variations, will follow 

 their course steadily until a halt is called either by germinal or by 

 personal selection. When a given plant is exposed to these new and 

 artificial conditions, the changes in question make their appearance 

 sooner or later, and follow their course, and go on increasing as long 

 as that is compatible with the harmony of the structure and function- 

 ing of the plant, this depending, as in all individual development, 

 on the struggle between the parts, that is to say, on histonal 

 selection. Only in this respect is the utility or injuriousness of 

 the change of importance, for personal selection, the struggle between 

 individuals, does not affect plants which are under cultivation. 



That such modifications may increase and may persist through 

 many generations, even with asexual multiplication, depends upon the 

 fact that the budding cells contain germ-plasm, as well as the germ- 

 cells, and if particular determinants of the germ-plasm in general are 

 caused to vary by these new influences, the variation may be trans- 

 mitted from bud to bud, from shoot to shoot, and so go on increasing 

 as long as the new conditions persist, as well as in amphigonic (bi- 

 sexual) reproduction, where they are transmitted from germ-cell to 

 germ-cell. It is not inconceivable that an individual adaptation, that 

 is to say a useful adjustment, might be effected in the course of asexual 

 reproduction, although it is improbable that direct influences would 

 give rise to just those changes which would be useful under the new 

 conditions. But there are a number of cases which have been inter- 

 preted in this way. In several of the cultivated plants named, the 

 reproductive organs have themselves degenerated, either only the 

 male, or only the female, or both at the same time ; and some observers, 

 accepting the hypothesis of an inheritance of functional modifications, 

 have regarded this as the direct result of disuse during the long period 

 of asexual reproduction. 



Leaving out of account this erroneous presupposition, we may ask 

 how asexual reproduction, such as that of the potato by tubers instead 

 of by seed, which has gone on exclusively for several centuries, could 



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