CHEMICAL PHENOMENA IN LIFE 



precipitated solid colloids or gels. From the small 

 size of these separated parts the whole protoplasm 

 must have the appearance of a foam formed by 

 gel walls, inclosing in its meshes colloids of more 

 liquid state. This hypothesis is not without 

 support from experiments. The eminent zoologist 

 Biitschli, of Heidelberg, has shown for many 

 colloids, both inorganic and organic, that they 

 have a foam-like structure which may be in some 

 cases observed through the microscope. Evidently 

 such foam-like structure in protoplasm must 

 facilitate the great variety of chemical processes 

 carried on contemporaneously in the narrow field 

 of a microscopical living cell. 



These structures can be transitory as well 

 as permanent. It is very probable that in the 

 course of evolution the former gave origin to the 

 latter. A problem of great interest is the question 

 of the nucleus. We know that the lowest organ- 

 isms, such as Bacteria and the blue-green algae 

 called Cyanophyceae, do not contain a typical 

 nucleus. In the Protozoa the nuclei are in many 

 cases of much more primitive structure than in 

 higher animals. In the highly organised plants 

 and animals the structure of the nucleus is so 

 intricate, as is seen particularly in the process 

 of the cleavage of nuclei, that the problem of 

 nuclear structure cannot be longer considered 

 a chemical one. The nucleus rather acts as a 

 special organism in the cell. To a certain 

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