THE LIVING SUBSTANCE. \\ 



tures during relaxation, such areas are very common. The 

 most beautiful and regular structure of this sort I have seen 

 was in an immature and unfertilized minnow Q.gg. In the 

 protoplasm of Hydra also exist such areas. 



That the appearances, described and figured here, can be 

 explained as an optical illusion, grounded in maladjustment of 

 focus, it is impossible to allow. The actual thickenings of the 

 meshwork, which are common in strial phenomena, are other 

 instances and proofs of the existence of a finer foam between 

 alveoli of the structure of Butschli,and with powers inadequate to 

 resolve this a greater amount of Continuous Substance than is 

 compatible with acceptance of Biitschli's structure as basic can 

 be readily seen in innumerable cases. 



The reader is asked to compare this figure with the drawings 

 in Biitschli's work from preserved material, and even from life, 

 which represent, indeed, veritable and distinct structures of 

 Biitschli as they are formed by natural or artificially forced 

 organization of the elements. 



The reticulum, then, is not in all, or even in most, cases a 

 mere structureless film of homogeneous substance between the 

 vesicles of Biitschli's structure; but a compound and highly com- 

 plex mass of protoplasmic foam, capable of the same phe- 

 nomena as are areas formed of the structure of Biitschli ; which 

 latter is often seen to be directly formed, or evolved, from it 

 by just such changes.^ 



There are protoplasmic structures and organs, and even or- 

 ganisms, whose whole mass is less than that of the interal- 

 veolar substance of Biitschli's structure in many cases ; and yet 

 within their limits takes place a full series of life activities dif- 

 fering in no essential respect from those characterizing large 

 masses of living substance. 



Biitschli himself concedes to the structure associated with his 

 name considerable range in size, — from ^ to i /x. 



Even in areas where this special structure is marked; and can 

 be readily seen to be characteristic ; as in Protozoa, and in early 

 stages of Metazoan embryos, there are intermixed vesicles of 



^ For full evidence of these assertions, the reader must turn to later portions of 

 this paper. 



