316 Tuberculosis 



almost colorless, and then removed to the slide by means 

 of a section-lifter. The water is absorbed with filter paper, 

 and then the slide is heated over a Bunsen burner until the 

 section becomes shining, when it receives a drop of xylol 

 balsam and a cover-glass. 



It is said that sections stained in this manner do not 

 fade so quickly as those stained by Ehrlich's method. 



Gram's Method. The tubercle bacillus stains well by 

 Gram's method and by Weigert's modification of it, but 

 as these are general methods by which many different 

 bacteria are colored, they are ill adapted for differentiation, 

 especially when the other methods are not more difficult. 



Isolation and Cultivation. The best method of ob- 

 taining a culture of the tubercle bacillus from sputum, 

 pus, etc., is to inoculate a guinea-pig, allow an artificial 

 tuberculosis to develop, kill the animal after a couple of 

 months, and make cultures from the center of one of the 

 tuberculous glands. 



The sputum or other tuberculous material used for inocula- 

 tion may be injected beneath the skin by a hypodermic 

 syringe, or placed in a little subcutaneous pocket made by 

 snipping the skin of the abdomen with scissors and dis- 

 secting it loose so that the fragment is easily introduced. 

 The animal is allowed to live for a month or six weeks, 

 and then killed. The autopsy is performed according to 

 directions already given. An enlarged lymphatic gland 

 with softened contents or a nodule in the spleen is usually 

 selected for the culture. An incision is made into it with 

 a sterile knife, or with a rigid sterile platinum wire, and 

 some of the contents removed and planted upon blood-serum, 

 as recommended by Koch; glycerin agar-agar, as recom- 

 mended by Roux and Nocard; glycerinized potato, as re- 

 commended by Nocard ; upon coagulated dogs' blood-serum, , 

 as recommended by Smith, or upon coagulated white of egg, 

 as recommended by Dorset. The inoculated tubes must 

 be kept in an incubator at the temperature of 37-38 C. 



Piatkowski* suggests that for the cultivation of the 

 tubercle bacillus and other "acid-proof" organisms, advan- 

 tage be taken of their ability to resist the action of for- 

 maldehyde. The material containing the acid-proof organ- 

 ism is mixed thoroughly with 10 c.c. of water or bouillon 



*" Deutsche med. Wochenschrift," June 9, 1904, No. 23, p. 878. 



