666 



Tuberculosis 



such media than upon blood-serum. The growth upon "glycerin 

 agar-agar" resembles that upon blood-serum. A critical study of 

 the relationship of massive development and glycerin was made 

 by Kimla, Poupe, and Vesley,* who found that the most luxuriant 



growth occurred when the culture-media contained 



from 5 to 7 per cent, of glycerin. 



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



isolating the tubercle bacillus has been published by 



Smith, f 



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

 in a sterile flask, where it is allowed to coagulate. The serum 

 is removed with a sterile 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 distilled water 4 parts. The whole is 

 then carefully shaken without making a froth, and dispensed 

 in tubes, 10 cc. to a tube. The coagulation and sterilization 

 he effects by once heating to go'C. for three to five hours. At 

 the Henry Phipps Institute in Philadelphia this medium was 

 employed with thorough satisfaction 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, in- 

 stead of the ordinary test-tube with the cotton-plug. The pur- 

 pose of the ground-glass cap is to prevent the contents of the 

 tube from drying during the necessarily long period of incuba- 

 tion; that of the tubulature, to permit the air in the tubes to 

 enter and exit during the contraction 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 eggs 

 makes them particularly adapted for the purpose. 



Fig. 273.— 

 G 1 a ss-capped 

 culture -tube 

 used by Theo- 

 bald Smith for 

 the isolation of 

 the tubercle 

 bacillus. 



The medium is prepared by carefully opening the egg and 

 dropping 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. — Pawlowski§ was able to isolate the bacillus upon potato. 

 Sander found that it could be readily grown upon various vegetable 



* "Revue de la Tuberculose," 1898, vi, p. 25. 

 t "Transactions of the Association of American Physicians," 18 

 p. 417. 



I "American Medicine," 1902, vol. in, p. SSS- 

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



vol. XIII 



