330 NATURAL SCIENCE. May, 



He cites this as an admission on the part of Romanes " that it is, to 

 say the least, no better than an even chance whether their influence 

 be good, bad, or indifferent." What Romanes means is that it does 

 not matter how slight the adaptive effects of the conditions may be ; 

 if they are inherited at all, they will be present in all the individuals 

 exposed to the conditions, and will be increased in every generation ; 

 whereas before a variation can be selected, it must be supposed to 

 have ' selection value ' — that is, must be large enough and important 

 enough to give a better chance of life and reproduction to its 

 possessor than other individuals have. This is one great advantage 

 of the Lamarckian theory, that a character which is constant in a 

 whole species may be explained without assuming that it is either of 

 selective value, or correlated with something of selective value. In 

 fact, the idea of advantage or benefit to the organism belongs 

 essentially to the selectionist view. All that the Lamarckian requires 

 is that certain effects which he sees to be produced in the individual 

 by response of living units to stimulation shall be cumulative, and 

 then the modifications which we know to have occurred must 

 necessarily follow. The effects of stimulation in its widest sense may 

 be life-preserving or life-destroying ; the hypothesis is that they are 

 definite and cumulative. 



Where the question of chance or fortuitous variations comes in I 

 fail to understand. It is notorious that the selection theory assumes 

 the occurrence of fortuitous variations, although with the under- 

 standing that fortuitous means unexplained only. But the assertion 

 that the effects of conditions on the individual, or acquired characters, 

 which alone I have considered in this article, are fortuitous is simply 

 a contradiction of universal experience. 



We find, therefore, on careful analysis, that Brooks conceives 

 the effects of environment on the individual to be of two kinds ; first, 

 the kind of which the enlargement of a muscle by exercise is an 

 instance, and, secondly, the others. Those of the first kind are due to 

 structural adjustments for bringing them about. According to the 

 Lamarckian view, all adaptations, at any rate all adjustments con- 

 cerning whose action and efficiency there is no dispute, have arisen in 

 the same way as the enlargement of a muscle by exercise ; and the 

 assertion that structural adjustments for rendering them possible 

 exist in organisms is just what Lamarckians contend. Therefore, on 

 this point Brooks agrees with Lamarckians; but whereas he supposes 

 that these structural adjustments have to be explained, Lamarckians 

 believe that they are merely the fundamental properties of proto- 

 plasm, namely, irritability and the power of assimilation and repro- 

 duction. The ' other ' effects of conditions are those which confer 

 no particular benefit on the organism. To take a trivial instance, a 

 young man who takes to an open-air colonial life develops muscles 

 and skeleton and senses to such an extent that he can ride, shoot, and 

 work with marvellous skill and endurance. At the same time his 



