CHANGES IN SCIENTIFIC OPINION 11 



has disposed of the simpler mechanical explanation, 

 which at first seemed to be sufficient, in favour of 

 another and far more complicated solution of the 

 difficulty. 



These and other difficulties, which it will be the 

 business of this book to bring forward, have led 

 many men of science to abandon the mechanical ex- 

 planation of nature as inadequate, and have caused 

 them to endeavour to substitute for it a further 

 theory of living matter. Thus Dr. Haldane l says : 

 " In a living organism there is a specific influence 

 at work, which so controls all the movements of 

 the body and of the material entering or leaving it, 

 that the structure peculiar to the organism is 

 developed and maintained ". And again : " To any 

 physiologist who candidly reviews the progress of 

 the last fifty years it must be perfectly evident 

 that, so far from having advanced towards a physico- 

 chemical explanation of life, we are in appearance 

 very much farther from one than we were fifty years 

 ago ". As an American witness, Professor Wilson, 

 perhaps the most eminent exponent living of the 

 problems of cell-life, may be cited, and he tells us 2 

 that " the study of the cell has on the whole seemed 

 to widen rather than to narrow the enormous gap 



1 Nineteenth Century, 1898, ii., p. 400. 



2 The Cell in Development and Inheritance, Macmillan & 

 Co., 2nd ed., 1900, p. 434. 



