THE LIVING SUBSTANCE. 7 



In point of minuteness, also, many of the facts which can be 

 optically noted defy camera tracing, since the finest steel point 

 is still too coarse for the work. 



Visible Protoplasmic Structure. 



[6] The structure of protoplasm throughout the substance 

 of all living organisms examined, except where secondarily 

 altered, was found to be, as maintained by Biitschli, that of a 

 visco-fluid foam. 



This is thought to be amply proven by the following optical 

 appearances : 



1. By presence of an optical reticulum, such as described by 

 Biitschli. 



2. By presence very commonly, above and below, in proper 

 focal relation to this, of a blistered, or what might be termed 

 a shagreen-like appearance, which with inadequate powers looks 

 slightly granular, or uneven. 



3. Since in all cases, above or below the shagreen surface, 

 or the network, proper focus yielded a smooth expanse, variably 

 thick, of seemingly homogeneous protoplasm ; such expanse 

 being large or small according to the amount of the network 

 in one optical plane at any moment. 



4. By presence of protoplasmic films or pellicles interven- 

 ing between the substance and all contacts involving a 

 viscosity different from its own, whether internal or external 

 to the mass, whether of alien substances or of its own 

 substance. 



5. By spontaneous formation of like pellicles freely against 

 all such differences of contact, whenever and wherever they 

 arise. 



6. By spontaneous vacuolization taking place in even very 

 viscous areas ; also in homogeneous-seeming areas. 



7. By similar vacuolization under pressure, or action of re- 

 agents ; or as marking relaxed states of the substance ; and in 

 states heralding, or following, death. 



8. Finally it is proven by true protoplastic metamorphoses 

 and activities, not in fluid areas only, but in those which are, as 



