THE LIVING SUBSTANCE. 27 



is composed of a number of different areas, suddenly rounds 

 itself off and shows a smooth surface at the broken ends, while 

 at the same time the different areas fuse smoothly together 

 at this region and can no longer be distinguished apart. The 

 same experiment can be tried in higher muscular areas, as of 

 rotifers. 



In relaxed states, areas of the structure of Biitschli which 

 were before very viscid, become so fluid in seeming with respect 

 to that structure, that the protoplasm presents the appearance 

 of mixing freely with water. So with the finer structure ; 

 states of such viscidity as caused elasticity of the continuous 

 or interalveolar element, may be followed by relaxed states in 

 which the protoplasm proper of Butschli's structure seems 

 miscible with water. 



Such appearances as described above may characterize the 

 whole of a pellicular area or be distributed in lines or networks 

 within it, at varying distances from the surface. In these latter 

 forms, they furnish, at times, the only direct evidence of alveolar 

 structure; and they then prove also that there is organization 

 of the elements for physiological function.^ 



Upon formation of physical pellicles where the area of con- 

 tact, internal or external, involves a number of alveoli, there 

 seems to be a tendency in protoplasm to thicken the film so 

 formed by access of interalveolar material. 



In a similar manner, that is, by interalveolar material and out- 

 flow of what has been termed hyaloplasm from the endosarc, 

 ectosarc is formed. Almost all pellicles, certainly all those of 

 Butschli's structure, are in strict sense an ectosarcal formation, 

 no matter what position they hold in the mass. 



The viscosity of the continuous substance varies locally from 

 moment to moment, the changes being often miraculously 

 swift. From a very fluid state it will become rapidly so viscous 

 as to resist pressure after the manner of a stiff elastic bristle ; 

 and this may take place without change in size of the visible 

 foam structure. 



In such states it is as a rule markedly contractile; and com- 

 monly the assumption of organized contractile activities by an 



1 See Striation. 



