ii 4 SCIENCE PROGRESS. 



plexity of the phenomena exhibited by individual cells, say 

 by an amceba, is so great, the functions observed are so 

 many and so various in their kind that they can only be 

 explained by the assumption that protoplasm is an organised 

 body ? Taking the words of O. Hertwig as a fair ex- 

 pression of current opinions on the life processes of a poly- 

 cytial organism, " that the aggregate life processes of a com- 

 posite organism appear to be nothing more than the ex- 

 ceedingly complicated result of the individual life processes 

 of its numerous and variously functional cells," it is evident 

 that to the minds of Briicke and his successors the aggre- 

 gate life processes of the corpuscle of protoplasm called a 

 cell are nothing more than the highly complicated result of 

 the individual life processes of its numerous and variously 

 functional biophors. If they do not mean this, I am quite 

 at a loss to know what they do mean, or to understand the 

 relevancy of the so-called axiom laid down by Whitman, 

 that "function presupposes structure," or the meaning of 

 the statement expressed so often and with such obvious 

 satisfaction, that " the cell is an organism ". These sen- 

 tences, so terse and so epigrammatic, exercise a peculiar 

 fascination over most minds. To understand their exact 

 applicability to the question at issue they must be carefully 

 examined. Function presupposes structure. To the bio- 

 logist who makes a rapid mental survey of his experiences, 

 this appears to be a generalisation of universal truth. 

 Physiology, which draws its inferences almost exclusively 

 from the study of the higher animals, tells us that ultimately 

 every function of the composite organism is to be referred 

 to a particular group of cells, and that cells differ in kind 

 according to the different functions which they exhibit. So 

 much is this truth forced upon us that if conceivably a new 

 function were to make its appearance, we should immediately 

 search for the cell groups appropriate to the performance of 

 that function. So far so good, but before proceeding further 

 we must take note that the statement that function pre- 

 supposes structure is a generalisation founded on experience. 

 It is not an axiom as Whitman calls it, for an axiom is a 

 proposition which is self-evident, and this assuredly is not. 



