THE BIOLOGY OF THE CELL SURFACE 



solved in the water are several inorganic salts, chiefly 

 chlorides, carbonates, phosphates of sodium, potassium, 

 calcium, etc. 



The researches on the analysis of carbohydrates and on 

 the synthesis of sugar, on the analysis of proteins (espe- 

 cially nucleo-proteins) stand in the fore-front of bio- 

 chemical achievements. And yet, there remains much to 

 be learned of the chemical make-up of the cell. Farther 

 and more refined analysis may furnish a clue to a better 

 understanding of living matter as a complex of compounds. 

 Up to now chemical analysis tells us only what is found in 

 the living thing after it is killed. The very nature of 

 chemical analysis demands isolation of the protoplasmic 

 components as separate chemical entities and thereby sets 

 up an obstacle in the search for the chemical constitution 

 of the living state. To know even with absolute exactness 

 the chemistry of each compound in the once living cell does 

 not guarantee that we know how these are organized in life. 

 Moreover, living organization is dynamic whereas the 

 application of chemical analysis by necessity demands 

 destruction of the very space-time structure which Is the 

 changing organization characteristic of life. No single 

 datum now at hand warrants the assumption that the 

 chemistry of the cell In the chemist's test tube Is that of the 

 living cell. Indeed, the evidence points to the contrary. 



These shortcomings of chemical analysis of the living 

 thing have served to focus attention upon its physical 

 attributes. Many biologists, therefore, seek to determine 

 the physical diagnostics of non-living and living on the 

 one hand, and of the living before and after It Is killed, 

 on the other. 



The presence of water In large amount confers upon 

 protoplasm certain physical properties; similarly, the 

 remaining substances entering Into the composition of the 

 cell are responsible for other such properties. Recently, 



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