116 The Unitij of the Organism 



And since physics and chemistry have fused together as 

 regards many phenomena in their own special fields to pro- 

 duce a single two-])arted science, physical chemistry, natu- 

 ral history looks with much ho])efulness to this new science 

 for light on the "living matter" aspect of its problem. It 

 is almost certain that the apj)lication of pln'sical chemistry 

 to the study of organisms has actually made a good start 

 in the very (juarter which, as indicated above, the naturalist 

 would expect help from tlie new science. 



As regards the Cell, biochemistry, -prosecuted under the 

 guidance of physical chemistry, is bringing out facts and 

 formulating conceptions that are unmistakably organismal, 

 it seems to me, in their trend. Deferring to tlie biochem- 

 ist's predilection for the cell rather than for the organism, 

 let us reflect on how the problem of the cell presents itself 

 to the naturalist in one of its main aspects, that, namely, 

 of its existence owXy, that is, its phenomena other than those 

 connected with cell reproduction through division or other- 

 wise. The basal problem thus arising is : what is the cell's 

 constitution in virtue of which it is able so to transform the 

 matter and the energy flowing through it as to enable it to 

 carry out the various activities, contraction, secretion, 

 conduction of stimuli and so on, peculiar to it, and at the 

 same time maintain its identity as a space-occupying object; 

 that is, maintain its individuality? 



Place, now, alongside this formulation of the natural his- 

 tory problem of the cell's existence the following summary 

 statement of what the cell is to a biochemist who sees physico- 

 chemically: "But it is clear that the living cell as we now 

 know it is not a mass of matter composed of a congregation 

 of like molecules, but a highly differentiated system ; the 

 cell, in the modern phraseology of physical chemistry, is 

 a system of co-existing phases of different constitutions. 

 Corresponding to the difference in their constitution, dif- 

 ferent chemical events may go on contemporaneously in the 



