THE INUTILITY OF TRANSMISSION 69 



cannot now develop in the individual under any form of stimulus 

 neither under nutriment, nor use, nor injury. 



109. On the other hand, were the Lamarckian doctrine true, 

 every structure which was much used (e.g. the lower limbs of man, 

 and, in particular, the joints) would increase in size proportionately 

 to the amount of use with results disastrous to the co-adaption 

 of structures ; every structure which was little used (e.g. organs 

 of generation), or was not ' used ' (e.g. hair, bones of skull), or was 

 disused, would degenerate, and structures which were much exposed 

 to injury (e.g. wings of butterflies) would tend to deteriorate. 

 Evolution and degeneration would thus proceed on lines as 

 complex as the individual and with extraordinary results. Here, 

 then, again, if acquirements were transmissible, since species 

 would be affected as wholes, since almost every individual would 

 alter in the same direction, natural selection would have no scope. 

 The species would drift helplessly out of harmony with the 

 environment. In point of fact, therefore, the Lamarckian 

 hypotheses of heredity and evolution, when closely examined (i.e. 

 when we make rigorous deductive inferences of consequences), 

 are found not to be theories of adaptation at all ; and they are 

 always, not merely sometimes, incompatible with the Darwinian 

 hypothesis. 



no. It is obvious at a glance, that, if actual injuries and 

 growths (e.g. scars), which arose in response to injuries, were trans- 

 muted into characters which arose inevitably (because developed 

 under the stimulus of nutriment), in the absence of injury the result 

 would be, not adjustive, but distinctly harmful. Similarly, char- 

 acters which develop under the stimulus of use are particularly 

 useful when so developed. They possess a quality of usefulness 

 which is lacking in those developed under the stimulus of 

 nutriment a kind of unconscious' intelligence, as it were, which, 

 within the limits of possible development, enables the individual 

 to grow just the right characters to just the right extent. Thus 

 the muscles of the athlete, whose need is greater, are larger and 

 more efficient than those of the ordinary man ; but they diminish 

 when he goes out of training. The arms of the sailor tend to 

 develop more in proportion than his legs, whereas the reverse is 

 the case with the soldier. The heart and t kidneys develop beyond 

 the ordinary in disease when life depends on a response to an 

 increased strain thrown on them. The skin thickens and hardens 

 when and where such changes are useful. When the need is over, 

 all use-developments tend to disappear, and the organism is 



