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along certain lines of modification in accordance with definite gen- 

 etic laws becomes, in other words, more apparent in the later than 

 in the earlier substages of the ontogeny.* 



In order to give a clear and comprehensible example of the gen- 

 eral application of these laws I have quoted below several pages 

 from Buckman's interesting and instructive paper on " Some Laws 

 of Heredity and their Application to Man." f 



How the Transmission of Variation would Affect the Origin 



of Species. 



" It is not difficult to understand the origin of species if the sur- 

 mises that I have submitted, concerning the transmission of devel- 

 opmental variation, are correct. The greater and greater elaboration 

 of any particular features in, say, an adult male, as functional mod- 

 ification necessitated by environment, are transmitted to the male 

 sex alone, and appear earlier and earlier in that sex. The greater 

 and greater elaboration of these features results in the course of 

 time in the formation of a marked and distinguishing character 

 in the male sex ; and this character being transmitted in accord- 

 ance with the law of earlier inheritance ultimately appears early in 

 life in the male. Then the character tends to appear in the female 

 sex also, though why it does so is not clear. By such process, how- 

 ever, there arise both males and females which possess characters 

 different to those which their ancestors possessed. 



" By the t<me that this character, influenced by the law of earlier 

 inheritance, appears at an age early enough to be transferred to the 

 female, the male has probably either further elaborated this charac- 

 ter — which further elaboration is at first transmitted to the males only 

 ■ — or he has elaborated something else so much that it seems like a new 

 character which is transmitted in the same way. In course of time 

 this further elaboration, or this new character as the case may be, is 

 transmitted also to the females ; and so it becomes plain how, 

 merely by the gradual transmission of developmental variations, 

 both sexes of what may be called an incipient species, beginning 

 with a slight variation in one sex alone, are able to diverge wider 

 and wider from the original stock. 



"The same laws of transmission would of course hold good if 



*The application of this law, however, to the gerontic substages demands a longei di»s 

 cussion than can be given here, and must be deferred to future publications. 

 fProc. Cottcswokl Natur. Field Club, Vol. x, Pt. iii, pp. 23S-3-J2, L891-1892. 



