48 Heredity. 



ries and artificially fertilized, and when kept under ex- 

 actly the same conditions, develop into widely different 

 organisms, and as like things canrot, under like con- 

 ditions, give rise to different results, we are forced to 

 conclude that these eggs are not essentially alike, but 

 that each contains within itself in some form the organ- 

 ism to which it is to give rise — that individual develop- 

 ment is, in some sense, the unfolding of a germ which 

 already exists in the ^gg. There is no escape from this 

 conclusion, at least there is none which can be accei^ted 

 by the scientific student, and we see that logical thinkers 

 like Prof. Huxley are driven to conclude that the pro- 

 cess which in its superficial aspects is epigenesis, appears 

 in essence to be evolution. 



Darwiii^s Hypothesis of Pangenesis. 



In contrast to the views already quoted we have the 

 well-known pangenesis hypothesis of Darwin, an hypoth' 

 esis which is thoroughly one of evolution, since Darwin 

 believes that the whole organization of the species is 

 present not only in the Qgg but in the male cell also; 

 that each of these not only contains the comj^lete organ- 

 ization of the parent, but an indefinite series of similar 

 organizations, inherited from a long line of ancestors. 

 It is true that Darwin does not believe that each of these 

 ancestors is represented in the ovum and in the male 

 cell by a minute but perfect animal, like those imagined by 

 Bonnet, but he imagines what is essentially the same 

 thing, that each of the cells of each parent, and every cell 

 of each ancestor for a long and practically an unlimited 

 series of generations, is represented in each ovum and 

 each male cell by a germ capable of i^roducing that par- 

 ticular cell with all its distinctive characteristics. 



Darwin's original statement ( Variation, chaps, xxvii. 



