PLASM 



of the plasm in the monera (both chromacea and bacteria 

 and rhizomonera) and the primitive simplicity of their 

 life-functions do not dispose us to think that special 

 groups of molecules are to be distinguished in these cases. 

 Max Verworn has recently (1903) formulated his biogen- 

 hypothesis in the same sense, as a "critical-experimental 

 study of the processes in the living matter." He also 

 takes the active plasma-molecules, which he calls biogens, 

 as the ultimate individual factors of the life-process, and 

 is convinced that in the simplest cases the plasm consists 

 of homogeneous biogen-molecules. 



The hypothesis of Nageli (1884) and Weismann (1885) 

 is totally difi[erent from the hypothesis of the plastidules 

 and biogens as simple molecules of the plasm. Accord- 

 ing to this, the ultimate "vital unities" or individual 

 vehicles of the life-process are not homogeneous plasma- 

 molecules, but groups of molecules, made up of a 

 number of dififerent molecules. Nageli calls them 

 micella, and assigns them a crystalline structure. He 

 supposes that these micella are combined chainwise into 

 micellar ropes, and that the variety of the many forms 

 and functions of plasm is due to the different configura- 

 tion and arrangement of these. Weismann says: "Life 

 can only arise by a definite combination of different 

 kinds of molecules, and all living matter must be made 

 up of these groups of molecules. A single molecule 

 cannot live, can neither assimilate nor grow nor repro- 

 duce." I do not see the justice of this observation. 

 All the chemical and physiological properties which 

 Weismann afterwards attributes to his hypothetical 

 hiophora may be ascribed to a single molecule just as 

 well as to a group of molecules. In the simplest forms 

 of the monera (both the chromacea and the bacteria) the 

 nature of their rudimentary life can be explained on the 

 one supposition just as well as the other. Naturally, 

 this does not exclude a very complicated chemical 



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