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THE AMERICAN XATURALIST 



cells have entered upon an additional symbiosis with Cy- 

 anophyceae, chroniatophores or chlorophyll-corpuscles. 



Interesting and suggestive as are the speculations of 

 Mereschkowsky, they are nevertheless open to criticism 

 from many points of view. I will not enter here into 

 criticisms which I regard as beyond my competence. It 

 is for botanists to pronounce upon the notion that Bac- 

 teria, Cyanophyceae, and Fungi can be classified together 

 as a group distinct from all other living beings ; to decide 

 whether the protoplasm of the Cyanophyceae and Fungi 

 can be regarded as consisting of mycoplasm alone, and not 

 of a combination of nuclei and cytoplasm, such as is found 

 in true cells and represents, according to Mereschkowsky, 

 a symbiosis of mycoplasm and amceboplasm. I think I 

 am right in saying that botanists are agreed in regarding 

 Fungi as derived from green algae, and as possessing 

 nuclei similar to those of the higher plants. As a zoolo- 

 gist the point that strikes me most is the absence of any 

 evidence that true Monera, organisms consisting of cyto- 

 plasm alone, exist or could ever have existed. Meresch- 

 kowsky supposes that when the Monera came into being 

 they maintained their existence by feeding upon Bacteria. 

 In order to digest Bacteria, however, the Monera must 

 have been capable of producing ferments, and therefore 

 did not acquire this power only as the result of symbiosis 

 with Bacteria, unless it be assumed that the symbiosis 

 came about at the instant that amceboplasm came into 

 existence. There is, however, no evidence that cytoplasm 

 by itself can generate ferments. All physiological experi- 

 ments upon the digestion of Protozoa indicate that the 

 cytoplasmic body, deprived of the nucleus, can not initiate 

 the digestive process. Consequently the existence of 

 purely cytoplasmic organisms would seem to be an im- 

 possibility. 



For my part, I am unable to accept any theory of the 

 evolution of the earliest forms of living beings which as- 

 sumes the existence of forms of life composed entirely of 

 cytoplasm without chromatin. All the results of modern 



