THE PHYSIOLOGY OF SECRETION. 183 



have been so widely accepted on evidence of such an extraor- 

 dinary character. If we only assume that there is but one 

 mechanism of glandular secretion, — a false assumption to be 

 sure, but one which seems theoretically probable and hence 

 answers the prime requisite of a good hypothesis, — if we make 

 this erroneous assumption, then the facts of secretion become 

 so completely obscure that we are compelled to assume secre- 

 tory nerves and secretory vital activities to explain them. If, 

 however, the fact be recognized, which has stared us in the 

 face for years, that there are several ways in which secretions 

 are driven from glands, several of which mechanisms may 

 coexist in one gland, then the facts of secretion, with one or 

 two unimportant exceptions, become plain. 



In closing, let us point a moral to this physiological tale. 

 An explanation in science, whatever it may be elsewhere, is 

 the statement of a phenomenon in simpler known terms. It 

 is no assistance to science, but rather a scientific misdemeanor, 

 to propose as an explanation something far more complex and 

 difficult to understand than the facts explained. There is, to 

 be sure, a superficial simplicity in the assumption that there is 

 but one secretory mechanism common to all cells. But when 

 it becomes necessary to make new assumptions to bring the 

 theory into accord with observed fact the theory may be safely 

 regarded as false. It was so with the geocentric theory of the 

 universe — new epicycles had constantly to be added to account 

 for the planetary motions ; it was so with the Weismannian 

 theory of inheritance — units of a new order had constantly 

 to be invented ; it is equally true of the secretory nerve 

 theory. 



