CHAPTER II. 



STEUCTUEE AND CONSTITUTION OF THE 

 BACTEEIAL CELL. 



31. Chemical Composition of the Cell Wall. 



NAKED cells, i.e. those wherein the protoplasma is unprotected by 

 an envelope, are unknown amongst scliizomycetes, the body of the 

 cell being in all fission fungi shut off from the outer world by a 

 membrane or cell wall. Little is as yet known regarding its 

 chemical composition, but the few investigations that have been 

 made in this direction demonstrate that we have to do with a 

 structure which not only differs in different species, but also 

 undergoes alteration according to the dietary of the cell. 



The proximate assumption that the cell wall of the fission 

 fungi consists of cellulose cannot withstand searching criticism 

 except in rare instances. At present only one single species, viz., 

 the Bacterium xylinwn, examined by 0. LOEW and A. J. BROWN 

 (I.), for which this assumption is justified, is known. The cell 

 walls of this acetic acid bacterium exhibit, after a suitable purifica- 

 tion, the following chemical composition, ascertained by ultimate 

 analysis : 



Found. Calculated 



for[C 6 H 10 6 ]?i. 



Carbon 44.26 44-44 



Hydrogen 6.25 6.17 



Oxygen 49.49 49.39 



The cell wall of this microbe is stained blue by aqueous or 

 alcoholic solutions of iodine, by iodine and sulphuric acid, and 

 with iodo-chloride of zinc. In a work from the pen of DREYFUSS 

 (I.), dealing, however, chiefly with higher fungi, and therefore 

 preferably to be considered only in the second volume, a few 

 species of fission fungi were included in the scope of investigation 

 (e.g. a culture of hay bacillus obtained according to Eoberts' direc- 

 tions). These when tested for cellulose by iodine yielded affirmative 

 results. The amount was, however, only very small. According 

 to NENCKI and SCHAFFER (I.), the cell wall of certain putrefactive 

 bacteria contains nitrogen; but they do not give the names of 

 the species. 



