256 BACILLI PATHOGENIC IN MAN. 



In this species we not uncommonly find that the youthful 

 stages only appear as oval, egg-shaped cells, and that 

 under certain conditions, where the multiplication is very 



rapid, these young cells prepon- 

 derate; but the simultaneous 

 presence of older individuals 



, ,. , , 



showing a distinct rod shape, 

 enables us to determine that 

 Fig. 71. Pneumonia bacilli all the cells are bacilli, for if 

 x 70 - we had to do with the forms 



a. from cultivations. i i j j 



ft, from exudation showing which we are accustomed to 

 capsules. designate as cocci, we should 



only find round, or at most very slightly oval cells. 



The short bacilli grow very frequently in chains of two 

 to four members ; these forms are apparently the more 

 numerous, the more rapid is the multiplication, and 

 hence in these preparations the short forms show a 

 marked preponderance. 



In preparations which are obtained from the animal 

 body, but not in those taken from cultivations of the 

 bacilli, the organisms are surrounded by a sort of 

 staining of capsule. Each bacillus lies embedded in a gelatinous 

 the capsule. g k ea th which is evidently composed of a substance 

 similar to mucine, as shown by its solubility in dilute 

 alkalies, and its insolubility in acetic acid ; the sheath 

 stains faintly when treated in a certain manner with 

 gentian violet or fuchsine, and is thus rendered very 

 distinct. In order to demonstrate the capsules dis- 

 tinctly in sections, Friedlander recommends the follow- 

 ing method : place the sections for twenty-four hours 

 in acid gentian violet solution (concentrated alcoholic 

 solution of gentian violet 50 parts, distilled water 

 100 parts, acetic acid 10 parts), then decolourise in 

 *1 per cent, of acetic acid for one to two minutes ; 

 then treat with alcohol, oil of cloves, &c. Ribbert 

 employs for cover glass preparations a staining fluid 

 composed of 100 parts of water, 50 parts of alcohol, 12 

 of glacial acetic acid, saturated, when warm, with dahlia ; 

 the preparations are immersed in this solution only for 

 a very short time, then washed in water and examined. 



