THE LIVING SUBSTANCE. 41 



[38] I find in living protoplasm that the size of the vesicles 

 of Butschli's structure cannot be brought under any rule cor- 

 relative with their position in masses. 



In any portion they may be large or small, or they may be 

 either in turn, and their organized arrangement extend in any 

 direction. 



Except the fact that the pellicular formations are always of 

 the finer foam of the interalveolar stuff, it is impossible to 

 group in point of size the remarkably diverse structural facts 

 of protoplasm. 



The same results are attained by the same creature, within 

 short intervals of time, by widely different distributions of the 

 substance elements. Peripheral areas may be coarsely or finely 

 vesiculate. They may be very viscous and have a finely sub- 

 divided structure, and then one may group together numberless 

 instances of similar coincidence. They may be very viscous and 

 have a very coarse alveolar structure ; and here again one may 

 summon many like cases. They may be markedly fluid and 

 have either coarse or fine structure. A coarsely structured 

 area may at one moment be very fluid and at another very 

 viscid. The same is true of an area or mass having marked 

 viscosity. In such forms as Amoeba radiosa the substance 

 may be watched for days varying from moment to moment its 

 play amongst such phenomena. 



These changes of physical state are most instructive, for 

 they represent the characteristic powers and activities of the 

 living substance. 



AREAL DIFFERENTIATION. 



For substance differentiations, as found in general researches 

 among many, more or less scattered, organisms, it is difficult to 

 lay down general rules. It might seem well-nigh impossible, 

 so contradictory are the evidences when followed along some 

 lines. Yet it is hard to work long on the substance as such 

 without becoming sure that there are generalizations to be 

 made, and hardly to be escaped, since along other lines the 

 habit of the substance is clearly defined. 



[39] Thus much is certain, that wherever was found organized 



