JVLY 31, 1903.] 



SCIENCE. 



141 



cussion of biological questious, Lord Kelviu 

 is 'no better equipped than any person 

 of average intelligence.' 



The question at issue is how far 'me- 

 chanical explanations' can be given of the 

 phenomena of life. The view which for 

 the last half century has been taught by 

 physiologists may be stated as follows : All 

 the processes observed in living organisms 

 are of such kind as to admit of being in- 

 vestigated by the same methods as are used 

 in the investigation of the phenomena of 

 non-living nature— i. e., by measurement 

 of their time and place relations imder 

 vaiying conditions— in other words, by the 

 method of experiment. But, beyond the 

 limit thus stated, we have to do with 

 processes which can not be directly meas- 

 ured or observed. These are, first, the 

 mental processes, whether of man or of 

 animals, in respect of which the experi- 

 mental psychologist is imable to go beyond 

 the estimation of conditions and effects; 

 and, secondly, the processes of organic 

 evolution by which the organism grows 

 from small beginnings to such form and 

 structure as best fit it for its place in na- 

 ture. This is the doctrine which was pro- 

 fessed by Helmholtz, the founder of mod- 

 ern physiologv% as the result of those early 

 investigations which were embodied in his 

 well-kno-mi treatise on the 'Erhaltung der 

 Kraft,' in which he demonstrated more 

 clearly than had been done before that the 

 natural laws which had been established in 

 the inorganic world govern no less abso- 

 lutely the processes of animal and plant 

 life, thus giving the death-blow to the pre- 

 viously prevalent vitalistic doctrine that 

 these operations of life arc dominated by 

 laws which are special to themselves. He 

 thereby brought into one the before too 

 widely separated sciences of physiologj' 

 and physics. 



It was not until Helmholtz had been en- 

 gaged for some eight years in building up 



the new science of physical physiology that 

 the Giii-man physiologist and the English 

 physicist (W. Thomson) came into per- 

 sonal relation with each other at Kreuz- 

 nach. In one of Helmholtz 's letters to his 

 wife he tells of Thomson's 'surpassing 

 acuteness, clearness and versatility,' quali- 

 ties which impressed him so much that in 

 their intercourse he found himself to be 

 by comparison 'a dullard.' He was evi- 

 dently wrong. From the botanical point 

 of view, the future Lord Kehin was no 

 better than 'a person of average intelli- 

 gence. ' But, in all seriousness, it is surely 

 a mistake to suppose that biological prob- 

 lems appeal so little to the intellect that, 

 unless he is an expert, a man of transcend- 

 ent ability is incapable of dealing with 



them. 



J. Burdon-Sanderson. 



O.KIORD, May 9, 1903. 



I am quite impenitent at the irrelevant 

 rebuke of the Oxford Regius Professor of 

 Medicine. But he might represent what 

 I wrote with more precision. I did not 

 express so absurd an opinion as that Lord 

 Kelvin "was no better than 'a person of 

 average intelligence.' " Nor do we need 

 in this countiy a testimonial from Helm- 

 holtz to the contrary. "What I wrote was: 

 ' For dogmatic utterance on biological ques- 

 tions there is no reason to suppose that he 

 is better equipped than any person of av- 

 erage intelligence.' By 'equipped' I in- 

 tended that he is not prepared by technical 

 study of the problems on which he pro- 

 nounces judgment. 



Sir J. Burdon-Sanderson concludes bj' 

 saying: 'It is surely a mistake to .suppose 

 that biological problems appeal so little to 

 the intellect that, unle.ss he is an expert, 

 a man of transcendent ability is incapable 

 of dealing with them.' The first clause of 

 this sentence is obviously absurd ; the latter 

 is a simple fact. Any one who has taken 

 the trouble to read the admirable volumes 



