116 THE GENESIS OF SPECIES. [CHAP. 



either due to external conditions or to obscure internal 

 causes in the organisms which exhibit them. Moreover, 

 these modifications, from whatever cause arising, are capa- 

 ble of reproduction the modified individuals " breeding 

 true." 



The question is, whether new species have been de- 

 veloped by non-fortuitous variations which are insignifi- 

 cant and minute, or whether such variations have been 

 comparatively sudden, and of appreciable size and impor- 

 tance ? Either hypothesis will suit the views here main- 

 tained equally well (those views being opposed only to for- 

 tuitous, indefinite variations), but the latter is the more re- 

 mote from the Darwinian conception, and yet has much to 

 be said in its favor. 



Prof. Owen considers, with regard to specific origina- 

 tion, that natural history " teaches that the change would 

 be sudden and considerable : it opposes the idea that 

 species are transmitted by minute and slow degrees."" 

 " An innate tendency to deviate from parental type, oper- 

 ating through periods of adequate duration," being " the 

 most probable nature, or way of operation of the secondary 

 law, whereby species have been derived one from the 

 other." 18 



Now, considering the number of instances adduced of 

 sudden modifications in domestic animals, it is somewhat 

 startling to meet with Mr Darwin's dogmatic assertion 

 that it is " a false belief " that natural species have often 

 originated in the same abrupt manner. The belief may be 

 false, but it is difficult to see how its falsehood can be posi- 

 tively asserted. 



It is demonstrated by Mr. Darwin's careful weighings 

 and measurements that, though little-used parts in domes- 

 tic animals get reduced in weight and somewhat in size, 



17 " Anatomy of Vertebrates," vol. iii., p. 795. 



18 Ibid., p. 807. 



