THE LIVING SUBSTANCE. 19 



tube full of fluid which has a pinkish tint. By similar activi- 

 ties the end of the tube becomes very much thinned, and at last 

 bursts open, much as a bubble would, in the centre. The proto- 

 plasm then moulds itself about the rim and the tentacle is 

 ready for use. The whole process occupies a few moments. 



This is one of numberless instances, which go to show that 

 it is the interalveolar rather than the inclusion substance of 

 protoplasmic foams, which is the living substan'ce. 



Fluid alveoli of Butschli's structure are subdivided in a num- 

 ber of ways. They have been seen to be constricted, or pinched, 

 in two, precisely as large vacuoles are at times. This occurs 

 in the endosarc of amoebae ; in the formation of ectosarcal parts 

 and organs, and in other reorganizations of the elements. 

 They are broken up also by what appears to be a relaxation of 

 their lamellar substance, at the same time with the surround- 

 ing substance; for this latter at such times seems to lose in vis- 

 cidity and to become more or less mechanically vacuolated. 



They are at times penetrated by filose processes spun into 

 their interior from the interalveolar substance. Whether the 

 actual lamellar substance takes any active part in these proc- 

 esses could not of course be optically determined. In the 

 endosarc of Amoebae, where the phenomena were first ob- 

 served, the simple filose processes were seen to branch. In 

 the Vorticellid, Epistylis — in the somewhat larger alveoli of 

 whose cuticle the same thing was later seen — the simple filose 

 extensions were swiftly ramified, until a distinct network was 

 formed. From this, in some cases, a finer froth appeared to 

 be formed later, in what manner could only be conjectured. 

 The filose processes may spin quite across the alveolus and 

 become fused with the opposite wall, or return to the main 

 thread, or the wall whence they came. The process is best 

 described by likening it to characteristic activities of the Pro- 

 toplast Groviia. 



It is not impossible that there may exist already in the fluid 

 inclusion a fine network, invisible by reason of the tenuity of 

 the lamellar substance, and that the filose processes merely fol- 

 low the course of the lamellae, pushing between the yielding 

 vesicles very readily, by reason of a rather greater amount of 



