THE LIVING SUBSTANCE. 153 



these sets of phenomena may be locally isolated or have im- 

 portant relations with other substance organs. These physical 

 and chemical activities may alternate with, or be controlled or 

 pretermitted by, physiological activities which may also make 

 large use of them as opportunities. Of causative interactions 

 amongst any one alone of these sorts of phenomena, volumes 

 might be written, and still incalculably much remain for coming 

 centuries of research workers to write ; — and all three sorts 

 are actually interwoven and mutually transmutable as cause 

 and effect. 



Constant watching of function in the living substance gave 

 the following results. The function of any substance organ 

 would seem not to be due to peculiar powers or properties of a 

 locally segregated portion of an organism's substance ; but to 

 exist as specific temporary relations of a universally similar 

 substance with its specific conditionings. All the facts gath- 

 ered as to structure and habit of the living substance seem to 

 me to indicate that it is indeed identical in powers at all points 

 in organisms ; such seeming differences as it shows expressing 

 for the general substance, local habit of selection, organization 

 and use of chemical opportunities or inclusion material in rela- 

 tion to itself; and for the local substance, specific chemical, 

 physical, and physiological relations with these, influenced 

 more or less by various controls due to function of other areas. 

 Endosarc becomes ectosarc and there functions in character 

 of that mode of organization and opportunities. Ectosarc re- 

 turns to endosarcal areas to function there again in character 

 of the latter. These things are true of the substance com- 

 posing higher organisms too, for even here the substance was 

 seen to exchange special organized states or conditions for 

 those more primitive ; and, correlatively, its functions for more 

 primal habits of activity. This truth is already partially 

 known in a grosser form of its expression as a " conversion of 

 function " in organs ; but in the basis of these, in the true 

 substance organs, it is almost, perhaps quite, universal. I have 

 shown that in minuter structures the substance is in a state of 

 local flux, and that stability of visible structures is but a mask 

 for mutability and mutations of both function and finer struc- 



