84 Scientific Sophisms. 



convenient substitute for certainty. Thus, 

 e.g. 



" I cannot doubt that the theory of descent 

 with modification embraces all the members of 

 the same class." * And again : " I can indeee* 

 hardly doubt that all vertebrate animals having 

 true lungs, have descended, by ordinary genera- 

 tion from an ancient prototype, of which we 

 know nothing, furnished with a floating appa- 

 ratus or swim-bladder." " It is conceivable that 

 the now utterly lost branchiae might have been 

 gradually worked in by natural selection for 

 some quite distinct purpose, in the same 

 manner as . . it is probable that organs 

 which at a very ancient period served for respir- 

 ation, have been actually converted into organs 

 of flight." 8 



It would be sufficiently surprising, if we had 

 not been so long accustomed to it, to learn that 

 the possession of lungs which constitute the 

 fitness of the possessors for living, not in water, 

 but in air, betrays their aquatic origin. 3 But it 

 is much more surprising that men illustrious in 

 virtue of their scientific eminence should expect 



1 " Origin of Species," p. 484. 



* Ibid., p. 19 1. 



* " Land animals, which in their lungs or modified 

 swim-bladders betray their aquatic origin." (Ibid., p. 196.) 



