266 



BACILLI PATHOGENIC IN MAN. 



voir of water is in so far of importance for the cultiva- 

 tion, as by means of it the surface of the serum is kept 

 sufficiently moist, and preserved from drying during the 

 long time that it is kept in the incubator. 



If tubercular masses are placed on such nutrient 

 substrata (care being taken completely 

 to exclude other bacteria), and kept 

 permanently at 37 C., distinct multi- 

 plication of the tubercle bacilli can be 

 seen after about 14 days. The greatest 

 care must of course be employed to ex- 

 clude other bacteria, more especially 

 because the saprophytes as a rule grow 

 much more rapidly at the body tern- 

 perature, and, starting from a very small 

 number of individuals, may completely 

 occupy the surface of the soil before the 

 tubercle bacilli have even begun to 

 multiply. According to Koch, it is best 

 to commence the cultivations from the 

 lymphatic glands of a guinea-pig which 

 has been inoculated with tubercular 



F; s: ;;;.;:: i-;;., ,\'M 



sputum or tubercular organs, and has 

 been killed after about three or four 

 weeks. The skin is purified with cor- 

 rosive sublimate, and one of the swollen 

 lymphatic glands is exposed, a series of 

 heated knives and scissors being em- 

 ployed for the purpose. 



Finally, the gland is cut through and 

 a portion of the interior is rubbed over 



Fig. 77. Cultivation x , n 



of tubercle bacilli the surface of the blood serum. In 

 on blood serum. gpite of tliese p recau ti ns, it is always 



well to inoculate a considerable number of tubes, for 

 some always become contaminated and useless. In the 

 incubator the tubes remain unaltered for 7 to 10 days ; 

 after this time, sometimes not till the fourteenth day, 

 dull white points and small flakes are formed on the 

 surface of the serum, these flakes having the appearance 

 of dry scales with a dull surface. At times they unite 



