THE PLACE OF BIOLOGY. 21 



unconnected with practical applications. There is evi- 

 dently much to be said in support of this view. The 

 Societies represented at this meeting are certainly not 

 devoted to what would ordinarily pass for practical 

 objects, and the interest which attracts so many persons 

 to science does not on the surface appear to be a practical 

 interest. 



It is nevertheless equally true that scientific work 

 excites our emotions in a high degree — a fact difficult 

 to explain if we are only pursuing the bare truth about 

 facts which in no way enter into our lives. What does 

 it matter to us, for instance, whether certain stimuli 

 cause an Arcella to produce bubbles of gas within its 

 protoplasm, or what gas these bubbles consist of ? Yet 

 why does such a problem seem to physiologists so in- 

 teresting as a matter of fact ? And why are we not 

 equally interested in endless other occurrences which 

 are constantly taking place around us, and about which, 

 if we were only seeking for abstract truth, we might 

 be expected to be equally interested ? Something is 

 evidently lacking in our provisional definition of the 

 aims of science, and we must try to get nearer to this 

 something. 



Let me try to follow out the case of the gas-bubbles 

 in the Arcella. Perhaps I may remind you that Arcella 

 vulgaris is a microscopic unicellular organism found in 

 rivers and ponds. It has a more or less transparent 

 shell, shaped something like the top of a mushroom, 

 with an opening where the stalk would come. Through 

 this opening it protrudes delicate pseudopodia, by means 

 of which it can creep about. When a living and healthy 

 Arcella is examined in a drop of water under the micro- 



