CRITICISMS ON " THE ORIGIN OF SPECIES " 187 



not, but, acquiring sexual characters, produces impregnated 

 eggs from whence A once more arises. 



No case of Agamogenesis is known in which, when A 

 differs widely from B, it is itself capable of sexual propaga- 

 tion. No case whatever is known in which the progeny of 

 B, by sexual generation, is other than a reproduction of A. 



But if this be a true statement of the nature of the process 

 of Agamogenesis, how can it enable us to comprehend the 

 production of new species from already existing ones ? 

 Let us suppose Hyaenas to have preceded Dogs, and to have 

 produced the latter in this way. Then the Hyaena will 

 represent A, and the Dog, B. The first difficulty that 

 presents itself is that the Hyaena must be asexual, 

 or the process will be wholly without analogy in 

 the world of Agamogenesis. But passing over this 

 difficulty, and supposing a male and female Dog to 

 be produced at the same time from the Hyaena stock, the 

 progeny of the pair, if the analogy of the simpler kinds 

 of Agamogenesis * is to be followed, should be a litter, not 

 of puppies, but of young Hyaenas. For the Agamogenetic 

 series is always, as we have seen, A : B : A : B, etc. ; whereas, 

 for the production of a new species, the series must be A : B : 

 B: B, etc. The production of new species, or genera; is 

 the extreme permanent divergence from the primitive stock. 

 All known Agamogenetic processes, on the other hand, end 

 in a complete return to the primitive stock. How then 

 is the production of new species to be rendered intelligible 

 by the analogy of Agamogenesis ? 



The other alternative put by Professor Kolliker the 

 passage of fecundated ova in the course of their develop- 

 ment into higher forms would, if it occurred, be merely 

 an extreme case of variation in the Darwinian sense, greater 

 in degree than, but perfectly similar in kind to, that which 

 occurred when the well-known Ancon Ram was developed 



* If, on the contrary, we follow the analogy of the more complex 

 forms of Agamogenesis, such as that exhibited by some Trematoda 

 and by the Aphides, the Hyaena must produce, asexually, a brood of 

 asexual Dogs, from which other sexless Dogs must proceed. At 

 the end of a certain number of terms of the series, the Dogs would 

 acquire sexes and generate young ; but these young would be, not 

 Dogs, but Hyaenas. In fact, we have demonstrated, in Agamogenetic 

 phenomena, that inevitable recurrence to the original type, which 

 is asserted to be true of variations in general, by Mr. Darwin's 

 opponents ; and which, if the assertion could be changed into a 

 demonstration, would, in fact, be fatal to his hypothesis. 



