400 NATURAL SCIENCE [December 



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 pro- 

 cess 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 pre- 

 cisely, for, no doubt, while the cultivated species was undergoing 

 evolution 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 of all or many of the ancestors 

 are commingled or are latent in the final result, the adult — Weis- 

 mann's theory of germinal selection for instance, or Mr Galton's 

 theory, which supposes that, on the average, one quarter of the 

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

 eighth from the grandparent, one-sixteenth from the great grand- 

 parent, and so on. Were such theories true there could be no 

 retrogression except through reversed selection, for the more evolved 

 ancestors would for ever tend to make their influence felt. But 

 plainly retrogression occurs in the mere absence of selection. 

 Moreover, if it be true that the organic world has arisen through 

 the preservation and accentuation of favourable variations, and if 

 it also be true that ontogeny is a recapitulation of phylogeny, then 

 it seems to me that it must be further true that there is necessarily 

 a greater tendency towards retrogression than towards evolution. 

 For all atavistic variations must tend towards retrogression ; where- 

 as all evolutionary variations need not constitute extensions of 

 the previous evolution. They may result in divergencies in new 

 directions ; or may even constitute reversals of the previous evolu- 

 tion, as in those cases of which Keversed Selection takes advantage. 

 Given sufficient time, in the absence of selection, retrogression 

 must therefore necessarily ensue. 



The rationale of retrogression, I take it, is as follows : — 

 Suppose, as regards any character which has undergone evolution, 



