THE UNITY OF SCIENCE 25 



known types of chemical reaction or mixture, and kinds of 

 organic response that were once supposed to be phenomena 

 sui generis and mysterious can now be produced and regulated 

 at will by modifications of chemical or thermal conditions in 

 the organism's environment. This closer connection between 

 biology and chemistry, it is true, has partly been brought 

 about by new discoveries that have worked counter to that 

 other tendency which would assimilate chemistry more closely 

 to the conceptions and categories of physics. For one thing 

 that has made possible a nearer approach of chemistry to the 

 more complex and obscure science of biology is the recent ob- 

 servation of certain comparatively complex and obscure 

 chemical facts, which do not, I take it, lend themselves readily 

 to explanation as special cases of other, simpler, already- 

 known facts. But if these new chemical discoveries have not 

 made easier the fusion of that science with its neighbor 

 at its lower end, they have still made seemingly more prom- 

 ising the hope of stretching its borders so as to overlap its 

 neighbor at its upper end. Hence, paradoxical though it may 

 seem, those lately observed phenomena in chemistry which 

 look most incomprehensible and least capable of reduction to 

 mechanical equations are precisely those which have done 

 most to encourage the anticipation that biology may, with the 

 help of chemistry, be made what is called a mechanistic 

 science. I refer to the singular phenomena of catalytic ac- 

 tion. These, precisely because they thus far have seemed to 

 make an important part of chemistry more obscure (from the 

 point of view of mechantistic or energetic concepts), make it 

 also seem less remote from physiology ; since the action of re- 

 versible enzymes is suggestively analogous to processes of or- 

 ganic metabolism which used to be considered distinctive pe- 

 <:uliarities of living matter. Thus a gap in science has been filled 

 up, a discontinuity alleviated, at one point, even though there 

 has possibly been created ipso facto a new discontinuity at an- 

 other point. In the long run it has all gone to promote the 

 tendency towards the fusion of the contiguous sciences along 



