714 On Acquired or Somatic Variations. [Ibis, 



developmental processes taking place in the ovum will evi- 

 dently be correspondingly intensified. Among those processes 

 will be that of pigmentation, so that there need not be much 

 difficulty in accounting for the fact that the chick's nestling, 

 fledgling, or juvenile plumage will be richer in coloration 

 than that of a corresponding European chick, if, indeed, 

 such is actually the case — the point to be noted, and this is 

 obviously the crucial point, being that the darker pigmen- 

 tation is acquired and due to somatic influences and has, if 

 my contention is correct, no connection whatever with 

 germinal factors. 



It is therefore evident that if we take this view of the 

 case, the darker pigmentation of the Bermudan Goldfinch is 

 not inherited in the proper sense of the term, but is acquired 

 afresh after the fertilization of each ovum, so that if we were 

 to place the parent-birds in a less vigorous or less congenial 

 environment or in one less prone to produce intensification of 

 pigmentation, the coloration process would return to its 

 normal and original base-level. 



We may perhaps venture another step and deduce from 

 the above premisses that intensified pigmentary processes of 

 this kind play no part in the evolution of the species. They 

 would appear to be merely temporary expressions in space on 

 the .part of any given species at any given secular period ; 

 and, as compared with more deep-seated blastogenic mutations 

 or variations, either in the orthogenetic or fortuitous progress 

 of the species in Time, would appear to be superficial, tran- 

 sitory, and as it would seem from the point of view of the 

 genesis of new species, negligible. 



As Prof. Arthur Thomson* has written, "From an un- 

 biassed registration of all observed diflferences between the 

 members of the same S[)ecies there have to be subtracted all 

 peculiarities that can be reasonably interpreted as associated 

 with age and sex, or as individually-acquired somatic 



* " The System of Animate Nature " or the Gifford Lectures delivered 

 in the University of St. Andrews in the years 1915 and 1916, p, 433. 



