70 NATIONAL TRENDS IN BIOLOGY 



than the mere adding of another isolated fact to an 

 already large store of knowledge. Biologists, as well as 

 all other laboratory workers, know that we can under- 

 stand each other fairly well when we confine our speech 

 to definite scientific terms, but that we usually differ 

 greatly when we enter into philosophical speculation. 

 Scientists, therefore, have limited themselves to certain 

 physically demonstrable methods. 



Thus one biologist writes: 



''My own observations of other persons' attitudes tempt 

 me to say that as a rule they refuse to take Vitalism 

 seriously, and I do not know whether this means that 

 they have not thought about the possible limitations of 

 science, or whether, as in so many cases otherwise, they 

 are ultrapractical as an accidental habit of mind. 



"I am afraid many of us are more interesting as experi- 

 mental animals for psychologists to study than as monu- 

 ments of truth. 



"My own view of this question is : 'Science limits itself 

 voluntarily to what is reasonably demonstrable, using a 

 perceptive method with logical extensions.' As scientific 

 individuals, we have as much right to free and easy im- 

 agination, superstition, and the like, as anybody else. We 

 avoid these things for the sake of safety and security to 

 our field of knowledge. I would think it almost equally 

 unwarranted to state that either life is mechanism or that 

 life contains a vital element which we do not or possibly 

 cannot know. But science itself is a natural development 

 of the human mind. Physics and chemistry are practical 



