94 CRITICISMS ON " THE ORIGIN OF SPECIES " in 



may not be the expression of the common condi- 

 tions to which that particular patch of nebulous 

 fog, which may have been constituted by their 

 atoms, and of which they may be, in the strictest 

 sense, the descendants, was subjected ? 



It will be obvious from what has preceded, that 

 we do not agree with Professor Kolliker in think- 

 ing the objections which he brings forward so 

 weighty as to be fatal to Darwin's view. But even 

 if the case were otherwise, we should be unable to 

 accept the " Theory of Heterogeneous Generation " 

 which is offered as a substitute. That theory is 

 thus stated : 



"The fundamental conception of this hypothesis is, that, 

 under the influence of a gener;il law of development, the germs 

 of organisms produce others different from themselves. 

 This might happen (1) by the fecundated ova passing, in the 

 course of their development, under particular circumstances, into 

 higher forms ; (2) by the primitive and later organisms produc- 

 ing other organisms without fecundation, out of germs or eggs 

 (Parthenogenesis)." 



In favour of this hypothesis, Professor Kolliker 

 adduces the well-known facts of Agamogenesis, or 

 " alternate generation " ; the extreme dissimilarity 

 of the males and females of many animals ; and of 

 the males, females, and neuters of those insects 

 which live in colonies : and he defines its relations 

 to the Darwinian theory as follows : 



" It is obvious that my hypothesis is apparently very similar 

 to Darwin's, inasmuch as I also consider that the various forms 

 of animals have proceeded directly from one another. My 

 hypothesis of the creation of organisms by heterogeneous genera- 



