Isolation 725 



its parasitic nature, so that in the course of time it can be 

 induced to grow feebly upon the ordinary agar-agar, and that 

 prolonged cultivation destroys its virulence. 



Animal Tissues. Frugoni* recommends that the tubercle 

 bacillus be isolated and cultivated upon animal tissue and 

 organs used as culture-media. He especially recommends 

 rabbit's lung and dog's lung for the purpose. The tissues 

 are first cooked in a steam sterilizer, then cut into prisms, 

 placed in a Roux tube, an addition .of 6 to 8 per cent, 

 glycerin- water added, so as to bathe the lower part of the tis- 



Fig. 242. Bacillus tuberculosis; adhesion cover-glass preparation 

 from a fourteen-day-old blood-serum culture. X 100 (Frankel and 

 Pfeiffer). 



sue and keep it moist, and the whole then sterilized in the 

 autoclave. 



The organisms are planted upon the tissue, the top of the 

 tube closed with a rubber cap, and the culture placed in the 

 thermostat. The tubercle bacilli grow quickly and luxuriantly. 



Bouillon. Upon bouillon to which 6 per cent, of glycerin 

 has been added the bacillus grows well, provided the trans- 

 planted material be in a condition to float. The organism 

 being purely aerobic, grows only at the surface, where a 

 much wrinkled, creamy white, brittle pellicle forms. 



* "Centralbl. f. Bakt. u. Parasitenk.," I. Abl. Orig., 1910, un, 553. 



