THE WONDERS OF LIFE 



of crystalline forms, is capable in certain circum- 

 stances (as metasilicon) of becoming colloidal and form- 

 ing jelly-like masses of glue. This fact is the more 

 interesting because silicium behaves in other ways very 

 like carbon, is quadrivalent like it, and forms very 

 similar combinations. Amorphous (or non-crystalline) 

 silicium (a brown powder) stands in relation to the black 

 metallic silicon-crystals just as amorphous carbon does 

 to graphite-crystals. There are other substances that 

 may be either crystalloid or colloid in different circum- 

 stances. Hence, however important colloidal structure 

 may be for the plasm and its metabolism, it can by no 

 means be advanced as a distinctive feature of living 

 matter. 



Nor is it possible to assign an absolute distinction 

 between the organic and the inorganic in respect of 

 morphology any more than of chemistry. The instruc- 

 tive monera once more form a connecting bridge be- 

 tween the two realms. This is true both of the inter- 

 nal structure and the outward form of both classes 

 of bodies — of their individuality (chapter vii.) and their 

 r type (chapter viii.). Inorganic crystals correspond mor- 

 phologically to the simplest (unnucleated) forms of 

 the organic cells. It is true that the great majority 

 of organisms seem to be conspicuously different from 

 inorganic bodies by the mere fact that they are made up 

 of many different parts which they use as organs for 

 definite purposes of life. But in the case of the monera 

 there is no such organization. In the simplest cases 

 (chromacea, bacteria) they are structureless, globular, 

 discoid, or rod-shaped plasmic individuals, which accom- 

 plish their peculiar vital function (simple growth and 

 subdivision) solely by means of their chemical constitu- 

 tion, or their invisible molecular structure. 



The comparison of cells with crystals was made in 

 1838 by the founders of the cell-theory, Schleiden and 



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