Isolation 707 



Uhlenhuth and Xylander* investigated its usefulness and recom- 

 mend it highly for assisting in manipulating the tubercle bacillus. 

 The sputum or tissue supposed to contain these organisms receives 

 an addition of antiformin, by which the tissue elements, the pus cells, 

 the mucus and other objectionable substances, and bacteria are 

 quickly dissolved, leaving the tubercle bacilli uninjured. It is 

 then centrifugalized, the fluid poured off and replaced by sterile water 

 or salt solution, and the bacilli washed, after which they are again 

 centrifugalized and caught at the bottom of the tube. This sedi- 

 ment, rich in bacilli, may be immediately transferred to appropriate 

 culture-media, where the organisms frequently grow quite well, 

 or can be used for the inoculation of guinea-pigs. 



The most certain method of obtaining a culture of the tubercle 

 bacillus from sputum, pus, etc., is first to inoculate a guinea-pig, 

 allow artificial tuberculosis to develop, and then make cultures from 

 one of the tuberculous lesions. 



To make such an inoculation with material such as sputum, in 

 which there are many associated micro-organisms that may destroy 

 the guinea-pig from septicemia, Koch advised the following method, 

 with which he never experienced an unfavorable result. 



With a sharp-pointed pair of scissors a snip about }4, cm. long is 

 made in the skin of the belly- wall. Into this the points of the scissors 

 are thrust, between the skin and the muscles for at least i cm., and 

 the scissors opened and closed so as to make a broad subcutaneous 

 pocket. Into this pocket the needle of the hypodermic syringe 

 containing the injection, or the slender glass point of a pipet con- 

 taining it, is introduced, a drop of fluid expressed and gently rubbed 

 about beneath the skin. When the inoculating instrument is with- 

 drawn, the mouth of the pocket is left open, A slight suppuration 

 usually occurs and carries out the organisms of wound infection, 

 while the tubercle bacilli are detained and carried to the inguinal 

 nodes, which usually enlarge during the first ten days. The guinea- 

 pigs usually die about the twenty-first day after infection. 



The guinea-pig is permitted to live until examination shows the 

 inguinal glands are well enlarged, and toward the middle of the third 

 week is chloroformed to death. The exterior of the body is then 

 wet with I : 1000 solution of bichlorid of mercury and the animal 

 stretched out, belly up, and tacked to a board or tied to an autopsy 

 ' tray. The skin is ripped up and .turned back. The exposed ab- 

 dominal muscles are now washed with bichlorid solution and a piece 

 of gauze wrung out of the solution temporarily laid' on to absorb the 

 excess. With fresh sterile forceps and scissors the abdominal wall 

 is next laid open and fastened back. With fresh sterile instruments 

 the spleen, which should be large and full of tubercles, is drawn 

 forward and, one after another, bits the size of a pea cut or torn off 



*"Arbeiten a. d. kaiserlichen Gesundheilsamte," 1909, xxxi, 158; "Centralbl. 

 f. Bakt. u. Parasitenk.," Referata, 1910, xlv, 686. 



