THE BACTERIAL CELL 



of other toxic agents, retaining their viabihty, for example, after ex- 

 posure to 5% sodium hydroxide or sulfuric acid. In order to account 

 for these strikingly different susceptibilities, many theories have been 

 proposed which assume that the bacterial groups vary with reference 

 to cellular permeability, presence of certain lipids in the cell mem- 

 branes, acid-base properties of the cell body, etc. Thus, observations 

 of electrokinetic behavior and of affinity for dyes at different pH levels 

 suggest that the cell material in the colon-dysentery-typhoid group 

 (Gram-negative) is less acidic than in the Gram-positive bacterial 

 species (pneumococci, staphylococci, streptococci, anthrax bacilli, 

 etc.) (1,20). The acid-fast bacilli (e. g., tubercle bacilli) produce 

 astonishingly high concentrations of a variety of lipids which gives 

 them marked hydrophobic properties (2,23). All the Gram-negative 

 species readily yield in solution phospholipid-protein-polysaccharide 

 complexes which constitute 5-10% of the total cell weight; similar 

 complexes have not been obtained from the Gram-positive organisms 

 (16,18). Recent observations have established a correlation between 

 ability to retain the Gram stain (correlated with greater susceptibility 

 to many antiseptics) and the presence around the cell of a magnesium 

 ribonucleate complex (5,10). All these facts provide examples of the 

 type of chemical information which results from the analysis of the 

 biological behavior of the cell and which will undoubtedly reveal 

 important differences of structure between the different bacterial 

 groups. 



The specific antibodies produced as the result of the injection 

 of bacterial antigens into the animal body have provided another set 

 of reagents that have yielded important information of a cytochemical 

 nature. The immune reaction to any one type of bacterial cell is not 

 a simple phenomenon, since bacteria are made up of a multiplicity of 

 chemical constituents many of which elicit the production of specific 

 antibodies. In other words, the injection of one type of bacterial cell 

 usually results in the production of several antibodies, each one of which 

 is directed against one particular cellular component. These different 

 cellular constituents obviously bear a definite spatial morphological 

 relationship to each other in the intact cell. Some are masked by 

 membranes and become exposed only as a result of cellular disintegra- 

 tion; others are peripherally disposed and in direct contact with the 

 environment. This stratification of cellular structures affects the im- 



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