SIZE AND STEUCTUEB OF THE BACTERIAL CELL. 



29 



absent. Capsulated forms are met with most often when 

 staining the bacteria that may be present in the fluids of 

 the animal body. Such forms are therefore met with oc- 

 casionally in saliva, sputum and in blood. Certain species, 

 however, may give rise to pronounced capsules, when grown 

 on artificial media (Fig. 5 a). 





<5i 



® 



Fig. 5. Capsulated bacteria, drawn with camera lucida, Zeiss one- 

 twelfth and ocular 2. a— Anaerobic bacillus isolated from hiuman feces, 

 capsules formed on glucose agar; ^ — Micrococcus tetragenus with cap- 

 sules, from blood of mouse— compared with red blood cell; f— Lanceolate 

 diplococcus of pneumonia with capsules — above this a red blood cell show- 

 ing false capsule, due to shrinkage in drying. 



The chemical composition of the soil influences the" 

 formation of the capsule. Thus, the leuconostoc, when 

 grown on sugar media, develops remarkably large capsules, 

 whereas in the absence of sugar this gelatinization of the 

 cell-wall does not take place. It is evident that the capsule 

 is not a degenerative product, but a normal reaction 

 induced by certain constituents of the medium. 



While the presence of capsules gives rise to slimy 

 growths, it must not be inferred that they are the invariable 

 cause of a slimy consistence. Bacteria may actually secrete 

 a mucin-like sticky substance, and as a result the liquid 

 will be slimy although no capsules will be found surround- 

 ing the individual cells. Instances of slimy milk, beer, 

 wine, etc., from causes of this kind are not uncommon. 



The detection of the presence of a capsule is not always, 

 an easy matter. Frequently, as a result of manipulation 

 capsule-like forms may be met with. This is invariably 

 the case when the bacteria are present in an albuminoua 



