THE LIVING SUBSTANCE. 



165 



leading into expansion, extension and intensification of the 

 powers of the substance; — that is, it may have opened the 

 way to, or even enforced, an ectosarcal set of substance habits. 

 Much stress has been already laid upon formation and function 

 of ectosarcal areas. They are indeed of almost unbounded 

 importance in the history of the substance and organisms. 

 Through these areas alone does the substance attain its most 

 complete control of environment; through these alone it struc- 

 turally reaches its higher life of the senses, of perception, of 

 thought, of psychological growth and reach of function, all of 

 which things are rooted in vesicular organization of irritability 

 and contractility; — for in these areas the living substance is 

 set free, fed, and stimulated, for fullest, highest and most 

 characteristic self-expression. 



A single vesicle of the structure of Biitschli forms for the 

 continuous substance a true organ, and when there are many 

 whose interactions of causes and opportunities make up an 

 organ, or set of functions, useful to the general substance or- 

 ganism, — there has been formed within the mass a second- 

 ary organism. However incidental their origin, each set of 

 functional interrelations extends and conditions and makes 

 more dependent the true primary substance organism, and, as 

 we have known, may even obscure this as cause and end. In 

 numerous ways, local substance organization could become 

 responsive to internal or outside stimulus or influence. Over- 

 nutrition, relative osmotic values of inclusions, dialysis as well 

 as surface tension, — all these things are doubtless fruitful 

 causes of origin and grouping of vesicular structures. Sub- 

 stance habit is clearly guided and to some extent controlled by 

 chemical and physical conditionings, and it is likely that of 

 all such opportunities the living substance organism neglects 

 in the long run no one that fits in well with its inherent or 

 established lines of habit. It is to be kept well in mind that 

 as far as we can go in the series, the continuous substance is 

 still complex organism with specific controls and habits and 

 conditionings. 



The greater stability of the coarser structure can create and 

 support more stable activities, form, functions, tendencies, and 



