APPENDIX E 247 



most stringent selection is now able to achieve is to preserve, not 

 to improve, the race. It is therefore plain that, owing to the 

 increasing tendency towards reversion, rapid evolution rapidly 

 slows down, till, even in the presence of stringent selection, it 

 practically ceases. 



But perhaps the most striking proofs of the present theory 

 are furnished by certain cultivated plants (for instance, the apple), 

 which are usually propagated by means of slips and suckers — 

 that is, by detached portions of the individual. Practically 

 speaking, the most favourable individual of a species has been 

 chosen and multiplied by means of slips, the rest of the species 

 being eliminated ; and in each new seminal generation the 

 process has been repeated. Such plants, therefore, have been 

 evolved by a tremendously severe process of selection, resulting 

 in an evolution much more rapid than is possible among animals 

 or annual plants. But now, supposing we chose any one of these 

 highly divergent varieties, and, without using any selection, bred 

 from seed alone, what again would happen? There is ample 

 evidence leading us to believe that, in the vast majority of 

 instances, the variety would swiftly (that is, in a very few 

 generations) revert to something very like the wild stock from 

 which it originally descended, — but not to the wild stock precisely, 

 for, no doubt, while the cultivated species was undergoing evolu- 

 tion in one direction, it was, under the changed conditions, 

 undergoing retrogression in other particulars, and in these the 

 reverted varieties would differ from the wild stock. 



I need not dwell longer on the tendency such plants and 

 animals have towards retrogression. The facts are notorious. 

 But it seems to me that these facts are strongly adverse to all 

 those recent theories of heredity to which I have alluded, and 

 which suppose that each ancestor is not represented in turn 

 during the ontogeny, but that the characters pf all or many of the 

 ancestors are commingled or latent in the final result, the adult — 

 Weismann's theory of germinal selection, for instance, or Mr 

 Gallon's theory, which supposes that, on the average, one-half of 

 the total heritage of an individual is derived from the parents, one- 



