OEIGIX OF THE SPECIFIC TYPE 307 



species appears, so to speak, as a vital crystallization, or to use Herbert 

 Spencer's phraseology, as an equilibrium of living matter, which 

 becomes displaced from time to time, and passes over into a new state 

 of equilibrium, being transmuted into a new species, something like 

 the pictures in a kaleidoscope. The species is thus something con- 

 ditioned from within, which must be as it is and could not be 

 otherwise, just like a crystal which crystallizes in one particular 

 system and not in another; it must be just thus or it could not be 

 at all. From the point of view of this theory it would be easy to 

 understand that the thousands or millions of individuals composing 

 a species all agree in essentials — that a specific type exists. 



But this conception can hardly be entirely correct, although 

 there is some truth at its foundation, namely, that germinal variations 

 which arise independently are the basal roots of all transmutation. 

 But the species is not simply the result of these internal processes, it 

 is not even mainl}^ so ; it is not the result of an internal, definitely 

 directed developmental force, even if we attempt to think out such 

 a force in a purely scientific or mechanical, instead of a mystical, 

 sense. It seems clear to me that the species is not a life-crystal in the 

 sense that it must, like a rock-crystal, take form in a particular way 

 and in no other for purely internal reasons and by virtue of its 

 physical constitution ; the species is essentially a complex of adapta- 

 tions, of modern adaptations which have been recently acquired, 

 and of inherited adaptations handed down from long ago — a complex 

 which might ([uite well have been other than it is, and indeed must 

 have been different if it had originated under the influence of other 

 .conditions of life. 



But of course species are not exclusively complicated systems 

 of adaptations, for they are at the same time ' variation-complexes,' 

 the individual components of which are not all adaptive, since they 

 do not all reach the limits of the useful or the injurious. All trans- 

 formations arise from a basis of spontaneous chance variations, just 

 as all forest plants grow from the soil of the forest, but do not all 

 grow into trees, the adaptive forms which determine the essential 

 character of the forest; for many species remain small and low, like 

 the mosses, grasses, and herbs ; and these too have a share, though 

 a subordinate one, in determining the character of the forest, which 

 depends definitely, though only partially, on the loftier growths. 



According to my view all adaptation depends on an alteration in 

 the equilibrium of the determinant system, such as must arise from intra- 

 germinal or even general fluctuations in the nutritive supply, aff'ecting 

 larger or smaller groups of determinants and causing variation in them 



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