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The Cell Concept 



Cytology may be defined as that branch of Science which deals with 

 the morphology and physiology of the cell. This definition raises the 

 question, "What is a cell?" The answer normally given is purely de- 

 scriptive, and a cell constructed according to this description would be 

 difiicult if not impossible to find in nature; indeed it is doubtful that such 

 a cell could even exist. A cell defined by a cataloguing of its contents, 

 valuable as such a definition may be from the point of view of classifi- 

 cation, scarcely provides a fundamental concept. Further, such a defini- 

 tion, accepted uncritically, may simulate a degree of knowledge not 

 consistent with the facts. A cell, whatever its morphological peculiarities 

 may be, is an integrated and continuously changing system. When it 

 ceases to have the power of change it also ceases to be a cell in the 

 biological sense and becomes a mere mass of disintegrating matter. 



Living organisms are made of protoplasm. How one may define proto- 

 plasm depends largely on one's point of view or that of one's favorite 

 authority. Protoplasm, like the cell, must be considered to be a system. 

 As such it cannot be defined adequately in terms of its chemical con- 

 stituents. Assuming that we could run a precise quantitative chemical 

 analysis of a portion of protoplasm, and it is possible to make a close 

 approximation to this, we are still unable to put together the ingredients 

 in the requisite quantities and thus produce living matter. No one has 

 yet made a synthetic cell and it seems unlikely that anyone will ever 

 do so, though amino acids and even low molecular weight proteins with 

 a tendency to make microspheres superficially similar to micrococci have 

 been reported (Fox, 1960). 



