THE EVIDENCE FROM MISSING LINKS. 147 



assuredly classified as distinct " species," and not as mere " varieties " 

 of one species so apparent are the differences in size, in colour, 

 in feather-arrangement, and even in the skeleton. Such an instance 

 stands, therefore, as a most typical case of the origin of new races or 

 of new species by the modification of the old ; and its consideration 

 will show us the futility of the demand that the original stock should 

 resemble the descendants to which it has given origin. There exists 

 no necessity that the rock pigeon should be intermediate between 

 any two of the four breeds just mentioned, or that any two of these 

 races say the fantails and pouters should in turn evince combina- 

 tions of the characters of each other. 



Mr. Darwin remarks of the pigeons and their history, that " if 

 we could collect all the pigeons which have ever lived, from before 

 the time of the Romans to the present day, we should be able to 

 group them in several lines, diverging from the parent rock pigeon. 

 Each line would consist of almost insensible steps, occasionally 

 broken by some slightly greater variation or sport, and each would 

 culminate in one of our present highly modified forms. Of the many 

 former connecting links, some would be found to have become abso- 

 lutely extinct, without having left any issue ; whilst others, though 

 extinct, would be seen to be the progenitors of the existing races. I 

 have heard it remarked as a strange circumstance," he continues, 

 " that we occasionally hear of the local or complete extinction of 

 domestic races, whilst we hear nothing of their origin. How, it has 

 been asked, can these losses be compensated, and more than com- 

 pensated ? for we know that with almost all domesticated animals the 

 races have largely increased in number since the time of the Romans. 

 But on the view here given we can understand this apparent contra- 

 diction. The extinction of a race within historical times is an event 

 likely to be noticed ; but its gradual and scarcely sensible modifica- 

 tion, through unconscious selection, and its subsequent divergence, 

 either in the same, or more commonly in distant, countries into two 

 or more strains, and their gradual conversion into sub-breeds, and 

 these into well-marked breeds, are events which would rarely be 

 noticed. The death of a tree that has attained gigantic dimensions 

 is recorded ; the slow growth of smaller trees and their increase in 

 number excite no attention." 



The true view of the matter really consists in our recognising 

 that the likeness and relation of new species or races to their parent 

 stock depend on the circumstances of human observation, and on 

 the exact lines along which the variation has proceeded. Occa- 

 sionally each likeness is apparent ; at other times, by the very manner 

 of development of the new species, it is non-existent. Nor must we 

 forget one all-important consideration, which, according to Pro- 

 fessor Huxley, Mr. Darwin himself somewhat overlooked. It is a 



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