THE LIVING SUBSTANCE. m 



protoplasmic extensions invisible to our strongest magnification, 

 having still the same structure, the same characteristic dis- 

 placements, which would yield to bettered tools the same 

 optical phenomena as belong to large organized masses, — such, 

 in short, as pertain to the characteristic physiological activities 

 of protoplasm. 



[102] Butschli found that mass has much to do with the rela- 

 tive character and duration of phenomena in his artificial foams. 

 The living substance seems to transcend such physical limita- 

 tions. That these statements are not merely wild speculation 

 or inference may be shown anew by a single instance, and it 

 is thought that the filose phenomena cited previously also bear 

 them out. Many others could be brought in evidence but for 

 lack of space. 



The cup-shaped film, or "collar " of many Choano-Flagellata 

 is so tenuous in greatest extension that when magnified eight 

 thousand diameters, though it may be visible obliquely and later- 

 ally, one cannot see it in direct, transverse, optical extension, 

 not even as a hair line; yet it is even then thicker than many 

 webs and veils Gromia extends. 



By addition of pigment to the water a double set of currents 

 can be demonstrated in this film. One current flows up and 

 out from the body over the outside of the collar to its edge. 

 Turning this, it then flows down the inside, back towards the 

 body substance with which it mingles. Small organisms brought 

 against the outside of the collar by rotary beat of the single 

 projecting flagellum that springs centrally from the anterior 

 end of the body, are carried along to the body substance which 

 engulfs them in usual protoplast fashion. ^ At times the collar 

 assumes considerable rigidity and the flow ceases for many 

 moments. I find that if a jar be given the cover glass, the fluid, 

 flowing film instantly contracts, taking the form of a truncated 

 cone. During this contraction, striae appear which run from 

 the top downwards, gradually thinning, fanning out, and fading 

 away as they near the base of the cone. Conversely, they are 



^ These phenomena were first described by Saville Kent whose faithful, patient 

 researches among minute organisms have yet to receive their full meed of appre- 

 ciation from biologists. In my own researches I have ever found Kent's work 

 preeminently accurate and fine. 



