IIG THE GENESIS OF SPECIES. [Ciur. 



cither due to external conditions or to o])scurc internal 

 causes in the org-anisnis which exhibit them. Moreover, 

 these niodilications, from whatever cause arising, are capa- 

 ble of reproduction — the modified individuals " breeding- 

 true." 



The question is, whether new species have been de- 

 velo})ed by non-fortuitous variations which are insign ill- 

 cant and minute, or whether such variati(.)ns have been 

 comparativel}' sudden, and of appreciable size and impor- 

 tance ? Either h}'^:)othesis 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 cliange 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 })eriods of adequate duration," being " the 

 most ])robable nature, or way of operation of the secondary 

 law, whereby species have been derived one from the 

 other." '' 



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 Jalse belief^'' that natural species have often 

 originated in the same abrupt manner. The belief ?nai/ be 

 false, but it is dillicult to see how its falsehood can be i)osi- 

 tively asserted. 



It is demonstrated by Mr. Darwin's careful weighings 

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

 tic animals get reduced in weight and somewhat in size, 



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

 >8 Ibid., p. 807. 



