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SCIENCE. 



[N. S. Vol. XVIII. No. 448. 



of Darwin's correspondence recently pub- 

 lished will easily inform himself that a 

 trained master mind may devote a lifetime 

 to biological problems and yet feel some 

 hesitation in pronouncing decisive judg- 

 ment upon them. An untrained master 

 mind may hesitate still more. The late 

 Lord John Russell was credited with the 

 capability at a moment's notice of per- 

 forming the operation for stone or taking 

 command of the Channel fleet. But such 

 versatility is believed to be rare. 'Trans- 

 cendent ability' will not enable a man 

 without previous training to either paint 

 an Academy picture or read the Hebrew 

 Bible. 



In his speech at University College Lord 

 Eelvin is reported to have said: 'Modern 

 biologists were coming once more to a firm 

 acceptance of something, and that was a 

 vital principle.' I deny the fact. And 

 Sir J. Burdon-Sanderson credits Helmholtz 

 with having given 'the death-blow to the 

 previously prevalent vitalistic doctrine that 

 these operations of life are dominated by 

 laws which are special to themselves.' He 

 explains 'these operations' to mean 'the 

 processes of animal and plant life.' Per- 

 haps he will tell us how he reconciles this 

 position with that of Lord Kelvin, on the 

 one hand, and that attributed by Lord 

 Kelvin to Liebig, on the other. The new 

 'vital principle' is only a resurrection of 

 the old 'vitalistic doctrine.' 



One word more. Sir J. Burdon-Sander- 

 son cites Helmholtz for the statement that 

 'the processes of organic evolution * * * 

 can not be directly measured or observed.' 

 If he will consult recent volumes of the 

 Philosophical Transactions or the pages of 

 'Biometrika' I think he will find reason, 

 in the light of recent research, to disagree 

 with him. 



W. T. Thiselton-Dyer. 



Kew, May 11, 1903. 



Tastes differ, of course ; but if I were in 

 Lord Kelvin's place I would rather be 

 criticized by Sir William Thiselton-Dyer 

 than defended by Sir John Burdon-Sand- 

 erson. His letter in your issue of to-day 

 is in three paragraphs. The first is sugar, 

 the second aloes, and the third sugar again. 

 This sort of sandwich is popular in the 

 nursery ; I fancy a man would sooner have 

 his dose undisguised. 



After vindicating Lord Kelvin's right to 

 speak with exceptional authority upon a 

 subject widely separated from those to 

 which he has devoted a long and strenuous 

 life. Sir John Burdon-Sanderson goes on 

 to show that he is entirely wrong. Lord 

 Kelvin drew a sharp line across nature, 

 and said that biologists are now engaged 

 in searching for the 'vital principle' which 

 alone can explain the facts of living mat- 

 ter. His mentor asserts the continuity of 

 nature; affirms that the processes appli- 

 cable on one side of Lord Kelvin's line are 

 equally applicable on the other; and de- 

 clares it to be the glory of Helmholtz that 

 he demonstrated more clearly than had 

 ever been done before that "the natural 

 laws which had been established in the in- 

 organic world govern no less absolutely the 

 processes of animal and plant life, thus 

 giving the death-blow to the previously 

 prevalent vitalistic doctrine." He does no 

 doubt add that some things, such as mental 

 phenomena in men and animals, are not yet 

 susceptible of explanation; but the same 

 holds good, as Lord Kelvin would be the 

 first to admit, about some of the most im- 

 portant phenomena of non-living matter. 



"VATien men of authority thus fiatly con- 

 tradict one another on fundamental ques- 

 tions, it is very hard for the humble in- 

 quirer to know what to believe. It be- 

 comes all the harder when neither the 

 physicists nor the physiologists can agree 

 among themselves. Sir John Burdon- 



