THE STRUCTURE OF THE BACTERIAL CELL 3 



or splitting plants (German, Spaltpflanzen). And of the two divisions 

 forming these Schizophyta the splitting algae are denominated the 

 sdiizophycoe (German, Spaltalgen), while the bacteria or splitting fungi 

 are called the schizomycetes (German, Spaltpilzen). The bacteria are, 

 thrivf'oi-e, oftm spoken of as the schizomycetes. Certain bacteria which 

 have been described as containing chlorophyll ought probably to be 

 grouped among the schizophycese. 



GENERAL MORPHOLOGY OF THE BACTERIA. 



The Structure of the Bacterial Cell. On account of the 

 minuteness of bacteria the investigation of their structure is 

 attended with great difficulty. When examined under the 

 microscope, in their natural condition, e.g. in water, they appear 

 merely as colourless refractile bodies of the different shapes 

 named. Spore formation and motility, when these exist, can 

 also be observed, but little else can be made out. For their 

 propei- investigation advantage is always taken of the fact of 

 their attinities for various dyes, especially those which are usually 

 chosen as good stains for the nuclei of animal cells. Certain 

 points have thus been determined. The bacterial cell consists 

 of a sharply contoured mass of protoplasm which reacts to, 

 especially basic, aniline dyes like the nucleus of an animal cell 

 though from this fact we cannot deduce that the two are 

 identical in composition. A healthy bacterium when thus 

 stained presents the appearance of a finely granular or almost 

 homogeneous structure. The protoplasm is surrounded by an 

 envelope which can in some cases be demonstrated by over- 

 staining a specimen with a strong aniline dye, when it will appear 

 s halo round the bacterium. This envelope may sometimes 

 oe seen to be of considerable thickness. Its innermost layer is 

 probably of a denser consistence, and sharply contours the 

 contained protoplasm, giving the latter the appearance of being 

 surrounded by a membrane. It is only, however, in some of 

 the higher forms that a definite membrane occurs. Sometimes 

 the outer margin of the envelope is sharply defined, in which case 

 the l.acterinm appears to have a distinct capsule, and is known 

 as a capsulated bacterium (vide Fig. 1, No. 4; and Fig. 62). 

 The cohesion of bacteria into masses depends largely on the 

 character of the envelope. If the latter is glutinous, then a 

 l:ir^e mass of the same species may occur, formed of individual 

 Bacteria embedded in what appears to be a mass of jelly. When 

 this occurs, it is known as a zoogloea mass. On the other hand, 

 it the envelope has not this cohesive property the separation of 

 individuals may easily take place, especially in a fluid medium 



