4M 



But while I consMcr that what year rc<-'i''wer has said on these 

 two essential points, falls within the iiraits of lej^itimate criticism ; I 

 do not consider that he is justified in much that he says by hn- 

 plication respecting my general views. 



In the first place, he conveys a totally wrong idea of the mode 

 of interpretation he criticizes. lie gives his readeis no con- 

 ception of the immense extensions which modern science has made 

 of the " mechanical theory," now applied to the solution of all phy- 

 sical phenomena whatever ; but he has deliberately restricted its ap- 

 plications in a way that produces an appearance of difficulty where 

 no difficulty exists. The common uses of the words "mechanical " 

 and " mechanist," are such as inevitably call up in all minds the 

 notions of visible masses of matter acting on one another by mea- 

 surable forces and producing sensible motions. In the absence of 

 explanations or illustrations serving to enlarge the conception thus 

 suggested, so as to bring within it the oscillations of the molecules 

 of matter, and the undulations of the molecules of ether pervading 

 all space, even the cultivated reader must carry with him an ex- 

 tremely crude and narrow idea of the " mechanist theory," and can- 

 not fail to be struck with the seeming absurdity of interpreting vital 

 phenomena in mechanical terms. But the reviewer says nothing 

 to prevent misconceptions so arising. He gives no hint that heat, 

 light, and electricity, are now all recognized as "modes of mo- 

 tion;" and that most of their phenomena are mechanically inter- 

 preted, while the rest are regarded as mechanically interpretable. 

 He does not explain that the "mechanist" theory in its compiehen- 

 sive form embraces actions such as those by which variations in the 

 solar spots cause variations in our magnetic needles, and actions such 

 as those th]-ongh which Sirius tells us what substances are contained 

 in his atmosphere. True he makes a passing reference to chemical 

 changes as being included by me under the conception of mechanical; 

 but he leaves this as a dead statement quite unintelligible to the 

 general reader ; and in the typical example he gives of my mode of in- 

 terpretation (the development of vertebrae by transverse strains) he 

 deliberately excludes the physio-chemical and chemical actions whicli 

 I imply as co-operating, and describes me as attributing the effects 

 entirely to the pressures and tensions caused by muscular move- 

 ments ! (See p. 408). Instead of the developed ideas of 

 Matter and Motion everywhere implied throughout the Principhs 

 of Biology, the reviewer leads everyone to suppose that I bring to 

 bear on biological problems nothing beyond the vulgar ideas of 

 Matter and Motion, and leaves me responsible for the ludicrous 

 incongruity ! 



That, however, which I regard as most reprehensible in his criti- 

 cism is the way in which he persists in representing the System oj 

 Philusophy I am working out as a materialistic system. Already he 

 has once before so represented it, and the injustice of so represent- 



