392 STUDIES, SCIENTIFIC AND SOCIAL chap. 



from one creature to another of a different nature. The 

 transition is by a purely normal and almost imperceptible 

 process of adaptation to new conditions, and in itself 

 furnishes no reason whatever why any useless character, if 

 it had constantly reappeared in the countless millions of 

 individuals during all the millions of generations of the 

 duration of the species, should at once disappear, or be 

 replaced by some new character equally universal, equally 

 invariable, and equally useless. 



I strongly urge, therefore, that the general causes 

 suggested by Darwin as possibly leading to the production 

 of useless specific characters, as well as the more special 

 causes enumerated by Mr. Romanes, do not apply to the 

 actual facts of variation and heredity so far as they are 

 yet known to us ; and further, that no attempt has been 

 made to show, even hypothetically, how, through the action 

 of known causes, such characters, when they do arise, can 

 become, first, extended to every individual of a species, 

 and then be totally obliterated as regards any portion of 

 the species which may become modified so as to constitute 

 a new species. Useful characters thus strictly limited are 

 the necessary and logical results of modification through 

 survival of the fittest. No agency has been shown to exist 

 capable of producing useless characters similarly limited. 

 And as it is beyond the powers of human reason to know 

 absolutely that any characters so limited as to be really 

 specific are and always have been useless, it is both un- 

 scientific and illogical to postulate such characters as 

 being present in all or many species, and therefore as 

 constituting an essential characteristic feature of specific 

 forms. 



The preceding discussion may, I hope, be considered 

 sufficient to show that useless specific characters, if they 

 exist, can only be the result of some comparatively rare 

 and exceptional conditions, and that they certainly are 

 not, as has been alleged, a general characteristic of species ; 

 but it may be as well to notice a few of the special cases 

 which have been adduced by Mr. Romanes and others as 

 examples of their existence or as illustrating their 

 formation. 



