THE VITAL IMPETUS 143 



than their own, that is, reserve determinants are 

 handed down in all cells capable of restitutive pro- 

 cesses, practically all the cells of the body. Or does it 

 contain only its own and those of the lens ? Then 

 this highly artificial operation was anticipated, an 

 absurd hypothesis which need not be considered. 



This particular mechanistic process (and no other 

 one is nearly so plausible) crumbles away before 

 attempts at verification, and it survives only by the 

 addition of subsidiary hypothesis after hypothesis. 

 In itself this demonstrates that it is an explanation 

 incompetent to describe the facts. 



What, then, is the "organisation"? It is some- 

 thing elemental, and we may just as well ask what 

 is gravity, or chemical energy, or electric energy. It 

 cannot be said to be any of these things or any com- 

 bination of them. " At present," says a skilful and 

 distinguished experimenter, T. H. Morgan, " we cannot 

 see how any known principle of chemistry or of physics 

 can explain the development of a definite form by the 

 organism or a piece of the organism." " Probably we 

 shall never be able," concludes Morgan, who is anything 

 but a vitalist. But does not this mean just that in 

 biology we observe the working of factors which are 

 not physico-chemical ones ? 



We have seen that the physiologist studies some- 

 thing very different from that which the embryologist 

 or naturalist studies. The former investigates a part 

 of the animal, arbitrarily detached from the whole 

 because the complexity of the functions of the simplest 

 organism is such that all of them cannot be examined 

 at once. He adopts the methods of physical chemistry 

 in his investigation and whatever results he obtains are 

 necessarily of the same order. Inevitably, from the 

 mere nature of his method, he can see, in the organism, 



