No. 029] BEHAVIOR AND ASSUIILATIOX 509 



dently the source of the " purposef ulness, " that has occa- 

 sioned endless biological discussion. The living organ- 

 ism, however, is teleological only to the same extent as 

 the ice-water-vapor system. 



These being the facts, the essential problem that con- 

 fronts us is a study of the physical and chemical aspects 

 of the equilibrium under the influence of a complex of 

 environmental factors. There must exist some degree of 

 correspondence between this equilibrium and the en- 

 vironment. Comparative morphological structure is evi- 

 dence of this and the same must obtain of chemical com- 

 position. The task before us is not so much to ascertain 

 the "function" of any particular substance or element, 

 as to acquire a knowledge of the equilibrium as a whole, 

 for it is only in relation to the other constituents that the 

 function of any one compound can be understood. The 

 need is consequently for a more detailed knowledge of 

 the interrelationships of the eliomieal constituents and 

 for determinations of how these n'lati(>nshii)s are altered 

 by changes in the organism itself. 'Hiis can i)robably be 

 carried out more readily with i)lants, hut the problem 

 demands more comprehensive analyses than any that 

 have hitherto been nunh'. Invest iuat ions with these 

 points in view are now \u\dvv way and the remarks in this 

 paper will serve as an introduction to them. A knowl- 

 edge of the conditions governing the change from one 

 phase to another within the organic system is a necessary 

 prerequisite to a more complete understanding of organic 

 equilibria. For the discussion of Le Chatelier's theorem 

 has shown, that in any reaction all the phases are in- 

 volved, and if the changes, such as tlie sign of the heat 

 effects, etc., accompanying the transformation of one 

 phase into another are knowm, it will be possible to pre- 

 dict by means of the theorem of T.e Chatelier the effects 

 that will be produced within the system by altering any 

 of its relations with the environment. 



Adams (MO, p. 74) says: ''Irritability may not be 

 causally explained, but it seems to obey these general 



