PLASM 



on that this is a purely chemical process, something like 

 catalysis in inorganic combinations; and for this neither 

 special organs nor fine elementary structures in the 

 plasm are needed. The "end" of their existence, self- 

 maintenance, is attained just as simply as in the catalysis 

 of any inorganic compound, or the formation of a crystal 

 in its mother-water. 



If we compare this very rudimentary life-process of 

 the monera with that of the highly differentiated protists 

 (diatomes, desmidiacea, radiolaria, and infusoria), the 

 biological distance between them seems to be immense; 

 and it is, naturally, far greater when we extend the com- 

 parison to the histona, the highly organized metaphyta 

 and metazoa, in the bodies of which millions of cells 

 co-operate in the work of the various tissues and organs. 



In the great majority of cells — either the autonomous 

 cells of the protists or the tissue-cells of the histona — 

 we can detect more or less definite and constant fine 

 structures in the plasm. We must regard these always 

 as phyletic, secondary products of the life-process, and 

 so call the differentiated plasm by the name of meta- 

 plasm. The very different interpretations of the micro- 

 scopic pictures which this metaplasm affords have led to 

 a good deal of controversy. In this the desire to discover 

 in these secondary plasma-structures the first causes of 

 vital action, or the real elementary organella of the cell, 

 has played a great part. The most important of the 

 theories that have been formulated are those of the 

 frothy structure, the skeletal structure, the fibrous struct- 

 ure, and the granulated structure of the plasm. All 

 these theories of structure apply to plasm in general, 

 but particularly to its two chief forms, thecaryoplasm of 

 the nucleus and the cytoplasm of the cell-body. 



Among the many different attempts to discover a 

 definite structure in living matter, the theory of the 

 frothy structure (also called the honeycomb structure) 



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