30 Journal of Comparative Neurology. 



of the nature of an equilibrium constructed from the inter- 

 actions of the cells implicated. 



In conclusion, it may be noticed that the ideas advocated 

 above have a very interesting bearing on the problem of the 

 origin of variation. The theory of the competition of parts 

 has taken strong hold of modern biology because it is becom- 

 ing more and more evident that the sphere of natural selection 

 must be greatly restricted and some appeal must be made to 

 forces residing within the organism. Even Weismann in his 

 extreme advocacy of natural selection has been forced to yield 

 a large place to the effects of inner coordinations. We suggest 

 that the nature of these coordinations is rendered much more 

 intelligible by conceiving of all these vital-nutritive processes 

 as equilibrated forces. If for any reason, a given part or tissue 

 of the body is in the least exaggerated, its part in this complex 

 coordination is increased and, accordingly, its reflex influence 

 on the organism as a whole, or its nerve centers, will be in- 

 creased and its quantum of the centrifugal currents will also be 

 increased, so that the tendency will manifestly be for the newly 

 created variation to go on increasing indefinitely until checked. 

 The next generation will inherit this tendency and we should 

 find that, in the absence of restraint, there would be the con- 

 stant likelihood of the appearances of strange monstrosities 

 with apparently unaccountable exaggerations of horn or spine. 

 It requires very little familiarity with paleontology to discover 

 that its records abound with cases in which no possible service- 

 ability would account for the absurd burlesques which have 

 been produced and only the comparative familiarity of existing 

 types blinds us to the same fact. While not denying that there 

 is a large element of useful adaptation in all cases (otherwise 

 they would never have been preserved), yet it will be admitted 

 that a very considerable proportion of the peculiarities and 

 often the deeper seated characters have no such explanation. 

 We should not be surprised at this, for it is apparent that the 

 slightest variation not directly hurtful will tend to perpetuate 

 itself. It may be said that all unnecessary parts will be elimi- 

 nated as sapping the nutrition of the body at large. This is an 



