PROTOPLASM. 51 
Thus what is spoken of as the structure of protoplasm is 
really the structure of the cytoplasm. It is often.specifically 
different in different cases. 
In regard to this structure, we know that it is very complex, but we 
are not sure of much more. For different experts see different appear- 
ances, even in the same cells. 
Thus some, ¢.g. Frommann, describe a network or reticulum, with 
less stable material in the meshes; others, ¢.g. Flemming, describe 
a manifold coil of fibrils; and others, ¢.g. Biitschli, describe a foam- 
like or vacuolar structure. It seems likely that the structure is different 
at different times, or in different cells. 
Professor Biitschli’s belief that the cytoplasm has a vacuolar structure 
is corroborated by his interesting experiments on microscopic foams. 
Finely powdered potassium carbonate is mixed with olive oil which has 
been previously heated to a temperature of 50°-60° C., an acid from the 
oil splits up the potassium carbonate, liberates. carbon dioxide, and forins 
an extremely fine emulsion. Drops of this show a structure not unlike 
that of cytoplasm, exhibit movements and streamings not unlike those 
of Amcebze, and are, in short, mimic cells. Just as a working model 
may help us to understand the circulation, so these oil-emulsion drops | 
may help us to understand the living cell, by bringing the strictly vital 
phenomena into greater prominence. 
Tt cannot be said, however, that subsequent research has corroborated 
the conclusion that cytoplasm has, in general, a vacuolar structure. 
There is increasing evidence of specific architectural organisation in 
different kinds of cells, and of the significance of infinitely small 
bodies—the plastosomes—which are included in the general cyto- 
plasmic matrix, and appear to be the vehicles of particular properties 
or formative potencies. 
What is certain is that the cell-substance is not homogene- 
ous like white-of-egg, but very heterogeneous and intricate. 
