THE LIVING SUBSTANCE. 



17 



its relations with the surrounding protoplasm ; whether, unlike 

 the major part of the network stuff, it is stable in position ; 

 or like this, in constant flux of intercourse with surrounding^ 

 areas ; whether the inclusions are in constant use by the sub- 

 stance ; or whether they are simply storehouses of chemical in- 

 fluence, withheld for special times or crises in the life-rhythms 

 of the mass, or portions of it : — all these questions now present 

 themselves as to the substances distinguished in Butschli's 

 structure ; and we need the answer. 



Inclusions may also be subdivided into microscopic and macro- 

 scopic. Microscopic, are those which lie within the lamellar 

 alveoli of Butschli's structure, or of the finer froth ; macroscopic, 

 those which are built up of these, forming, in any living mass, 

 areas, or structures, relatively large. 



[14] When dealing with the living substance strictly as 

 such, and with organisms as masses of protoplasmic foam; 

 all endo-skeletons, all vascular systems, all body cavities, 

 have for the substance, or the mass, the same value in a 

 physical sense as the alveolar inclusions have for the lamel- 

 lar substance. 



Even exo-skeletons arise in many cases as protoplasmic in- 

 clusions, and later, by withdrawal, or atrophy, of the living sub- 

 stance, become more strictly external. 



It is interesting that this statement, in at least one instance, 

 can be applied to the membrane of plants also. The cellulose 

 wall of very young Spirogyra filaments was seen to be covered 

 by a most delicate film of living substance, of which the alveoli 

 were hardly one-sixth the size of alveoli of Butschli's structure. 

 They were elongated and arranged in parallel rows. Most 

 curious of all was it that the rows of alveoli followed with 

 perfect sympathy the direction of the internal spirally twisted 

 chlorophyll bands, so that the surface under a lower power 

 appeared most delicately striated longitudinally; as if there 

 were in the nature of the whole plant substance the same 

 spiral tendencies. The inclusions appeared to be homogene- 

 ously fluid. In older specimens this outer film disappears; 

 either obliterated by the increasing deposits of cellulose, or 

 having itself migrated to the interior of the cell. The 



