4IO Weismanns Theories — 



mean by vitalism. At the beginning of this discourse I referred to 

 the anti-vitalistic tendency which accompanied the great advance in 

 knowledge that took place at the middle of the century. But even 

 at the height of this movement there was a reaction towards vitalism, 

 of which Virchow, the founder of modern pathology, was the greatest 

 exponent. Now, a generation later, a tendency in the same direction 

 is manifesting itself in various quarters. What does this tendency 

 mean % It has to my mind the same significance now that it had 

 then. Thirty years ago the discovery of the cell as the basis of 

 vital function was new, and the mystery which before belonged to 

 the organism was transferred to the unit, which, while it served to 

 explain everything, was itself unexplained. The discovery of the 

 cell seemed to be a very close approach to the mechanism of life, but 

 now we are striving to get even closer, and with the same result. 

 Our measurements are more exact, our methods finer ; but these very 

 methods bring us to close quarters with phenomena which, although 

 within reach of exact investigation, are, as regards their essence, 

 involved in a mystery which is the more profound the more it is 

 brought into contrast with the exact knowledge we possess of sur- 

 rounding conditions.' ^ 



These words point clearly to what we take to be one of 

 the profoundest and most important truths in the whole 

 range of science ; one which may be called the very truth of 

 truths of biological science. It is a truth which has the 

 most direct and important bearing upon all those laws of 

 life to the investigation of which Professor Weismann has 

 devoted so many years and so much labour. He is a worthy 

 worker in the cause of science, and yet, like not a few of his 

 fellow-workers, he strangely under-estimates and misrepre- 

 sents that good cause of which he is, in a subordinate field, 

 so zealous a servant. Scientific knowledge, 'par excellence, is 

 and must be the most complete, accurate, and certain know- 

 ledge attainable by man. We do and should speak of the 

 science of botany, the science of mathematics, the science of 

 history and biological science; but when we use the word 

 ' science ' simply by itself and without qualification, it should 



1 Nature, vol. xl. No. 1039, Sept. 26, 1889, p. 521. 



