Chapter IV 

 THE CHEMICAL CONSTITUENTS OF CYTOPLASM 



Proximate analysis of the cytoplasm:- It is impossible to analyze 

 the cytoplasm. Only the analysis of the protoplasm as a whole, 

 including the nucleus, can be obtained. When it is a question of 

 specifying the chemical constitution of the cytoplasm itself, we can 

 only have recourse to microchemical reactions which verify the 

 results obtained by proximate analysis but which can give only a 

 very inaccurate idea of the chemical constitution of the cytoplasm. 



It is especially the proximate analysis of protoplasm which will 

 give us an idea of the chemical constitution of the cytoplasm. But 

 before discussing the principal results obtained in this field, it is 

 important to stress the exceptional difficulties attending work of 

 this type. At the present time, we possess only analytical processes 

 with which to study the chemical constitution of living matter. 

 Now, protoplasm is killed by the least analytical attempt and one 

 is immediately reduced to working on dead matter, i.e., on a sys- 

 tem quite obviously modified. As for the sjmthesis of protoplasm, 

 living or dead, it has never been realized and in the present state 

 of our knowledge it even seems impossible of realization. What is 

 more, it is not known even how to make the principal substances 

 entering into the composition of living matter — the proteins or 

 lipides, which will be discussed later — or even how to make the 

 very numerous organic products, such as starch or cellulose, which 

 are generally manufactured in the cytoplasm. 



Now as Berthelot has said, "To know really the nature of 

 things, it does not suffice to destroy them. We must be able to 

 recreate them". Analysis teaches how a body may be torn down. 

 It does not indicate how it has been built up. Everything indicates, 

 on the contrary, that decomposition in most cases does not follow 

 in reverse direction the same steps as synthesis. The two processes 

 differ essentially in every respect from each other. These con- 

 siderations will make it possible to give the proper weight to the 

 data which we now possess on the chemical constitution of living 



matter. 



The Plasmodia of Myxomycetes are here again particularly fa- 

 vorable objects for analysis of living matter. They are made up of 

 naked protoplasm, i.e., there is no trace of those more or less thick, 

 always important, external envelopes which living matter secretes 

 at its surface in almost all organs. The Plasmodium of Myxomy- 

 cetes is, therefore, the most directly and easily accessible proto- 

 plasm. Several analyses have been published, that, for example, 

 of Lepeschkin in 1923 for the Plasmodium of Fuligo septica which 

 follows : — 



