Cultivation 



709 



a sterile 

 a sterile 



Dogs' Blood-serum. — A very successful method of isolating the 

 tubercle bacillus has been published by Smith.* 



A dog is bled from the femoral artery, the blood being caught in 

 flask, where it is allowed to coagulate. The serum is removed with 

 pipette, placed in sterile tubes, and coagulated at 75° to 76°C. 

 Reichel has found it advantageous to add to each 100 cc. of 

 the dogs' serum 25 cc. of a mixture of glycerin i part, and dis- 

 tilled water 4 parts. The whole is then carefully shaken with- 

 out making a froth, and dispensed in tubes, 10 cc. to a tube. 

 The coagulation and sterilization he effects by once heating to 

 9o°C.' for three to five hours. At the Henry Phipps Institute 

 in Philadelphia this medium was employed with thorough satis- 

 faction for the isolation of many different tubercle bacilli. 

 Smith prefers to use a test-tube with a ground cap, having a 

 small tubular aperture at the end, instead of the ordinary test- 

 tube with the cotton-plug. The purpose of the ground-glass 

 cap is to prevent the contents of the tube from drying during the 

 necessarily long period of incubation; that of the tubulature, 

 to permit the air in the tubes to enter and exit during the con- 

 traction and expansion resulting from the heating incidental to 

 sterilization. 



To the same end the ventilators of the incubator are closed, 

 and a large evaporating dish filled with water is stood inside, 

 so that the atmosphere may be constantly saturated with 

 moisture. 



Egg Media. — Dorsetf recommends an egg medium, 

 which has the advantage of being cheap and easily 

 prepared. Eggs are always at hand, and can be 

 made into an appropriate medium in an hour or two. 

 He also claims that the chemic composition of the egg 

 makes them particularly adapted for the purpose. 



The medium is prepared by carefully opening the egg and 

 droppping its contents into a wide-mouth sterile receptacle. 



The yolk is broken with a sterile wire and thoroughly mixed 

 with the white by gentle shaking. The mixture is then poured 

 into sterile tubes, about 10 cc. in each, inclined in a blood- 

 serum sterilizer, and sterilized and coagulated at 7o°C. on two 

 days, the temperature being maintained for four or five hours 

 each day. The medium appears yellowish and is usually dry, 

 so that before using it is well to add a few drops of water. 



Potato. — PawlowskiJ was able to isolate the ba- 

 cillus upon potato. Sander found that it could be 

 readily grown upon various vegetable compounds, 

 especially upon acid potato mixed with glycerin. 

 Rosenau§ has shown that it can grow upon almost any 

 cooked and glycerinized vegetable tissue. 



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 



* "Transactions of the Association of American Physicians," 1898, vol. xm, 

 p. 417- 

 t "American Medicine," 1902, vol. in, p. 555. 

 i "Ann. de ITnst. Pasteur," 1888, t. vi. 

 § "Jour. Amer. Med. Assoc," 1902. 

 II "Centralbl. f. Bakt. u. Parasitenk.," I. Abl. Orig., 1910, liii, sss- 



Fig. 280. — 

 G 1 a ss-capped 

 culture -tube 

 used by Theo- 

 bald Smith for 

 the isolation of 

 the tubercle 

 bacillus. 



