PROTOPLASM. 51 



Thus what is spoken of as the structure of protoplasm is 

 really the structure of the cytoplasm. 



Sections of fixed and stained cells often show a considerable com- 

 plexity of structure, and various appearances have been often described. 



Thus some, e.g. Frommann, describe a network or reticulum, with 

 less stable material in the meshes ; others, e.g. Flemming, describe 

 a manifold coil of fibrils ; and others, e.g. Btitschli, describe a foam- 

 like or vacuolar structure. 



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 5o-6o C. , an acid from the 

 oil splits up the potassium carbonate, liberates carbon dioxide, and forms 

 an extremely fine emulsion. Drops of this show a structure not unlike 

 that of cytoplasm, exhibit movements and streamings not unlike those 

 of Amoebae, 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. 



More recent work, especially with the ultra-microscope, points to the 

 conclusion that the reticular, fibrillar, and other complexities are, in the 

 main, post-mortem effects. There are definite formed bodies, such as 

 mitochondria and various plastids, in many cells, and there is often a 

 deposition of less labile material by the ever-changing protoplasm, but 

 the important fact is that protoplasm is a heterogeneous mixture in a 

 conoid State. 



