8i 



fallacy of the double hypothesis. Indeed, 

 there is a third hypothesis which plays a 

 silent part also. Father Wasmann says "that 

 the whalebone-whale only in the tertiary 

 period succeeded the toothed whale, which 

 may be regarded as its probable ancestor" 

 mark the "probable," and the double as 

 sumption, first of the succession (which is very 

 far from certain) and secondly of the relation 

 ship by descent. The first hypothesis then 

 destitute of every vestige of proof is, that the 

 whalebone-whale is descended from the toothed 

 whale. The second hypothesis which is the 

 one seeking for proof, is that the appearance 

 of the embryonic teeth is due to the biogenetic 

 principle. 1 In this particular case Father 

 Wasmann wishes to prove it by the appear 

 ance of the teeth in the embryo whales. And 

 this he does by the simple process of assuming 

 his first hypothesis to be a "fact." We have 

 already, elsewhere, called attention to this new 

 species of fallacy which consists in basing one 



iThis is the hypothesis which tells us that in ontogenesis, or the evo 

 lution of the individual, we have a reproduction of phylogenesis, or the 

 evolution of the race; in other words, that the individual embryo up to 

 maturity passes through all the forms through which the race has passed. 



