PATHOGENIC BACTERIA 143 



distinguishable from other cellular elements (Fig. 27). Most of the various 

 cytological methods used in investigating cell contents are applicable. The 

 principles of bacteria-staining are not different from those involved in the 

 staining of other cells, although in particular cases special technical pro- 

 cesses are necessary to success. For these any of the numerous handbooks 

 on bacteriological technique may be consulted. 



The isolation of pathogenic bacteria from diseased organs is effected 



\ N ^ 



V ^ \ 



^$mt$M& 



*txM&s$x$im. 



''temwigy&k* 



FlG. 27. Stained preparations of bacteria, from Ziegler's Lehrbuch d. allg-em. Patholog-ie, 8th ed., vol. i. a, 

 sputum of a consumptive, spread on a coverglass, and dried and stained with fuchsin and methylene blue; the 

 tubercle bacilli are red, cellular elements (pus cells) blue. 6, Gonococci {Micrococcus gonorrhoeae) in fresh 

 secretion, coverglass preparation : a, mucus with isolated cocci and pairs ; 6 and c, pus cells with and without cocci, 

 methylene blue and eosin. c, section through an anthrax pustule (stained by Grain s method), methylene blue and 

 vesuvine. Magn. a 400, 6 70x5, c 350. 



by the method of plate culture (p. 58). In some cases, tuberculosis for 

 instance, the centres of disease contain pure cultures of the specific bacteria, 

 and tubes of nutrient agar or gelatine can be inoculated direct. Much more 

 labour is entailed where the tissues contain a mixture of bacteria of different 

 sorts from which the pathogenic species has to be separated and deter- 

 mined. 



The requirements of pathogenic bacteria in artificial cultures differ 



