THE LIVING SUBSTANCE. 



71 



[79] It is these latter, the free filose phenomena, not amoe- 

 boid flow, which I find to be most universal, most characteristic, 

 and most fundamental in the living substance. 



Amoeboid flow is but filose flow organized over a sufficient 

 area to include to some considerable extent the structure of 

 Biitschli. Division between the two has been made on the 

 arbitrary ground of difference in relative size and shape of the 

 mass involved, and on acceptance of the structure of Biitschli 

 as the final structure.^ 



Filose spinnings from pellicles are so frequent that they can- 

 not be overlooked. To such cilia owe their origin, and it is 

 noteworthy that they arise with equal freedom whether the 

 pellicle be external or internal to the mass. Cilia are formed 

 by spinning from a pellicle of Biitschli's structure, or from the 

 pellicle of the finer froth. In the former case they are apt to 

 arise just above the apex of each alveolus of Biitschli's struc- 

 ture underlying the pellicle, and there is a quite definite ten- 

 dency to formation of alveolar layers beneath ciliated pellicles. 

 Because of viscidity of the interalveolar substance in such 

 layers, preservations give an appearance which observers have 

 described as " microsomes," each supporting a cilium. 



Where cilia arise from the pellicular substance of the finer 

 froth, they are very delicate, and seem to clothe the surface of 

 the pellicle evenly. In their presence it is not possible, 

 because of optical interference, to see the finer foam structure, 

 but from their number and evenness of distribution, as well as 

 their distance apart, it is hardly rash to say that they bear the 

 same relation to the finer alveolation of the pellicle that the 

 coarser cilia do to the structure of Biitschli. It sometimes 

 happens that the coarser cilia arise at points which correspond 

 to union of the continuous substance with the pellicular sub- 

 stance. I do not remember a case in which the coarser cilia 

 were scattered quite irregularly over a surface. 



Cilia often appear to be formed by splitting up of an undu- 

 latory membrane. I believe this to be to great extent an 

 optical illusion born of the simultaneous and harmonious 

 action of many cilia beating in time, then changing to a rhyth- 



1 See Substance as Organism. 



