INDIVIDUAL AND ANCESTRAL DEVELOPMENT 315 



investigate, or more useful to ascertain, than this: How are all 

 things formed by an univocal agent? How does the like ever gen- 

 erate its like? Why may not the thoughts and opinions now preval- 

 ent many years hence return again, after an intermediate period of 

 neglect?" 



Summing up the results of his investigation of this magnificent 

 proposition, which occupied him for many years, he says: "It appears 

 clear from my history that the generation of the chick from the egg 

 is the result of epigenesis, and that all its parts are not fashioned 

 simultaneously, but emerge in their due succession and order. For 

 the part that was at first soft and fleshy, afterwards, without any 

 change in the matter of nutrition, becomes a nerve, a ligament, a 

 tendon; what was a simple membrane becomes an investing tunic; 

 what had been cartilage is afterwards found to be a spinous process of 

 bone, all variously diversified out of the same similar (homogeneous) 

 material." 



It is more than two hundred and fifty years since this proof was 

 given that, so far as it is discoverable by our senses, individual de- 

 velopment is epigenesis, or new formation, and not the unfolding of 

 the preexistent; yet, dissatisfied with facts, we go on hunting, with 

 what we call our mind's eye, for an invisible substance of inherit- 

 ance, holding that development must be evolution in essence, however 

 epigenetic it may appear to sense. 



If I venture, at this late day, to point out that ancestral develop- 

 ment may be as epigenetic, from beginning to end, as individual de- 

 velopment, and that the species for which we are seeking is not, and 

 cannot be, in the germ, I do so because this proof is neither new nor 

 original with me. It is so old that many "up-to-date" zoologists 

 tell us it is antiquated, abandoned, no longer worthy the attention of 

 advanced thinkers. 



According to this view, the species is not in chromatin, nor in 

 germ-cells, nor in differentiated cells, nor in living beings at any stage 

 of existence, nor in the conditions of existence, because it is in that 

 reciprocal interaction between the organism and the rest of the natural 

 world which has been called the struggle for existence. Neither the 

 stability of species nor the mutability of species is in living beings, 

 because it is through extermination in the struggle of life that the 

 type is kept true to its kind, and also through this struggle that it 

 becomes changed. 



You will note that it is as great an error to locate species in the 

 external world as it is to locate it in germ-plasm. It neither exists 

 in the organism nor in the external world, because it is in the recip- 

 rocal* interaction between the two. The biological types, of which 

 those who call themselves statistical biologists tell us, are neither 

 external standards to which living beings approach and from which 



