322 SPECIFIC MICRO-ORGANISMS 



examination of the cerebrospinal fluid^ in nearly every case. The 

 filmy clot which usually forrns in such a fluid in a half hour after 

 drawing it is the most favorable material for examination. 



When a considerable amount of purulent or mucoid material 

 is available for examination and one has failed to find the tubercle 

 bacilli by the usual method of microscopic examination, it is 

 often advisable to try some method of concentration. One of 

 the common methods of general applicability is that of Uhlenhuth, 

 in which antiformin is employed to dissolve the tissue elements, 

 leaving the bacilli unchanged. Loffler's modification^ of the 

 Uhlenbuth method is a convenient one. The material to be 

 examined is mixed with an equal amount of 50 per cent anti- 

 formin and brought to a boil. This dissolves the sputum or 

 other material and serves to kill the bacilli. It is then cooled 

 and, for each 10 c.c, 1.5 c.c. of chloroform-alcohol (i : 9) is added. 

 The mixture is next violently shaken to form a fine emulsion, 

 and is then centrifugalized at high speed for 15 minutes. The 

 solid matter collects as a tough mass on top of the drop of chloro- 

 form and beneath the watery liquid. This mass is rinsed in 

 water, crushed between slides mixed with a little egg albumen or 

 with some of the original untreated exudate, spread, fixed, stain- 

 ed and examined in the usual way. The albuminous material is 

 necessary to make the preparation adhere to the slide. 



Allergic reactions are extensively employed in the diagnosis 

 of tuberculosis. Tuberculin is without particular effect upon 

 normal individuals but in the tuberculous individual it gives 

 rise to irritation and intoxication. The phenomenon is analogous 

 to that of anaphylaxis, the irritant or toxic substance being set 

 free from the tuberculin by the action of specific ferments pro- 

 duced and present in the body as a result of previous contact 

 with the tubercle bacillus and its products. The tuberculous 



^Holt: Amer. Journ. Dis. Children, Jan., 1911, Vol. I, pp. 26-36. Hemenway: 

 ibid., 1911, Vol. I, pp. 37-41. Koplik: Johns Hopkins Hosp. Bull., igi2. Vol. XXIII, 

 pp. 1 13-120. 



'^ Williamson: Journ. A. M. A., 1912, Vol. LVIII, pp. 1005-7. 



