The Evolution of the Sciences 



to the Dutch botanists, and after having acquired 

 more definite meaning at the hands of the 

 physicists it is being employed in biology to 

 elucidate questions of such importance as the 

 movements of the sap in plants and the con- 

 ditions of germination and fecundation. Other 

 subjects are attracting attention: the action 

 of enzymes, so strangely analogous to the action 

 of certain metals in the so-called colloidal state, 

 reduced to impalpable powders; the strange 

 analogies between micro-organisms and certain 

 crystals, and finally the study of the colloids which 

 physicists are just beginning, which should result 

 in valuable information from the physiological 

 point of view, because protoplasm, the funda- 

 mental living matter, belongs to the group of 

 colloids. A cellular physics is thus in course of 

 slow development; it may still be called 

 physiology, but its methods and technique are 

 borrowed from the sciences of inert matter, its 

 laboratories must be fitted for both, and, what is 

 more difficult in view of our present specialisa- 

 tion, it must find men equally familiar with 

 biological problems and the methods and 



apparatus of chemistry and physics. 



306 



