420 C. CLIFFORD DOBELL. 



The living" Micrococci, examined in the contents of the 

 large intestine immediately after removal from the lizard, 

 showed no very definite strncture. I have been unable to 

 convince myself of the presence of any internal structures 

 from an examiaation of living organisms alone. 



With stained preparations, however, the case is very 

 different, I have obtained the best results after fixation with 

 1 per cent, osniic acid or formalin, and after staining with 

 Giemsa's or Leishman's stain in the manner already described 

 (see p. 415). The following descriptions apply to organisms 

 treated in this manner. 



The Micrococci occur singly, in pairs, or in chains. They 

 are usually perfectly spherical, and have a diameter (in fixed 

 and stained specimens) varying fiom rather less than 1 fi, up 

 to 2 ju. All intermediate sizes may be found. It is possible, 

 ot" course, that the different sized forms are really different 

 species. They all occur together, and in company with many 

 other forms. But it is quite immaterial, for my purposes, 

 whether they are one species or one hundred, for they all show 

 a structure which is the same in each individual, and it is with 

 their structure that I am concerned. 



Every individual, after fixing and staining (cf. I'l. 17, 

 fig. 45), shows a uniformly coloured cytoplasm, a well-marked 

 cell wall, and acenti-ally situated, darkly staining body. This 

 central body is always present. It is roughly in the foi*m of 

 a spherical granule, but may appeal- more or less square or 

 triangular in optical section. It always takes up the chromatin 

 stain strongly. 



Among" the ordinary "resting" forms just described, a 

 number of dividing organisms can usually be found. The 

 details of the process of division can be followed in stained 

 specimens with great clearness, and present features of con- 

 siderable interest. 



Division — which results in the formation of two equal 

 daughter-cells — takes place as follows (see figs. 46-49). In 

 the first place, the central body becomes elongated — the cell 

 itself also exhibiting a slightly rod-like form — and assumes a 



