10 THE CYTOLOGY AND LIFE-HISTORY OF BACTERIA 



Valuable results have been achieved by the digestion of surface structures 

 with lysozynie and by various combinations of lysozynie, trypsin and other 

 proteins at specific values of pH, and by phase-contrast studies of the effects 

 upon the cell of antibodies active against cell-envelope components. (Section 

 L, below.) 



G: CLASSICAL CYTOLOGICAL PROCEDURES 



(3, II, 14, 18, 43, 51, 67) 



The cytological staining techniques which have been employed for plant 

 or animal cells arc often of value also in the case of bacteria. These are too 

 numerous to be dealt with in detail. 



Iron alum hacmatoxyhn and borax carmine have both proved useful in 

 demonstrating the bacterial nucleus. 



Cytochenncal techniques for the demonstration of polysaccharide food 

 reserves, fat globules and similar materials have been extensively utilised in 

 the investigation of bacteria, but the results achieved have been marred by 

 the absence of any attempt, in most cases, to preserve the natural appearance 

 of the cells. It is also the opinion of the author that these supposedly specific 

 staining reactions, of which the use of osmic acid vapour or the naphthol 

 dyes for lipids are fair examples, arc much less reliable than has been 

 supposed. 



The enigmatic nature of the majority of demonstrable granules in bacteria 

 is tacitly admitted by the practice of coining for them such titles as " meta- 

 chromatic granules " or " volutin " ; they have even been claimed to be 

 mitochondria. These granules are rarely apparent except in dried material, and 

 are often artefacts, although it is not denied that reserve foodstuffs, in the form 

 ot polysaccharides or lipids, may normally be present in the bacterial cell. 

 It is also beyond question that the nuclear bodies of bacteria have many times 

 been described in circumstances which have led to their being confused with 

 these and other unidentifiable granules. 



