TUBERCULIN REACTIONS 399 



dissected, and the lesions examined for bacilli. 1 Others inocu- 

 late two guinea-pigs, one subcutaneously in the abdomen, the 

 other intra-peritoneally. Negative results are nearly as valuable 

 as positive ones. 



In fceces, if definite yellow caseous particles can be found, these 

 should be picked out, and films made and stained. Antiformiu 

 may also be used. About 5-6 c.c. of faeces are mixed with 20 c.c. 

 of 15 per cent, aqueous antiformin in a conical glass, well agitated 

 and broken up, and an equal volume of the dilute antiformin is 

 then added. The mixture is allowed to stand for an hour, and 

 with the white curdy layer which forms, films are prepared, 

 stained, and examined. 



4. Milk. See section on milk (Chapter XXI). 



V. The opsonic method. The general mode of carrying this out 

 is described at pp. 259-263, the tubercle bacilli being suspended 

 in 1-5 per cent, salt solution. 



VI. Tuberculin reactions. The old tuberculin is used for diag- 

 nostic purposes ; it is not perhaps very safe. A dose of 0-0002 c.c. 

 is injected subcutaneously, and the temperature taken four- 

 hourly during the succeeding thirty-six hours. A rise of 2-3 F. 

 or more ensues a few hours after injection in tuberculous subjects. 

 If no reaction occurs another dose of 0-0005 c.c. may be given 

 after the lapse of some days, followed by a third one of 0-001 c.c. 

 if necessary. 



This method has now almost completely been superseded by 

 the cutaneous or by the ophthalmo reaction. 



The cutaneous tuberculin reaction. Von Pirquet discovered 

 that when tuberculin is introduced into the superficial layers of 

 the skin of tuberculous individuals, as in vaccination, a reaction 

 occurs consisting of the formation of a papule with redness, 

 slight swelling and exudation, and sometimes small vesicles. 

 This reaction is usually at its height twenty-four to forty-eight 

 hours after inoculation. In healthy individuals no reaction 

 follows the inoculation. The method is to scarify a small spot 

 on the forearm through a drop of a dilution of the old tuberculin, 

 and protect the patch with a simple dry dressing. Moro has 

 modified the method by applying the tuberculin to the skin in 

 the form of ointment. 



1 The results only apply to ordinary forms of tuberculosis, and not to 

 certain modified forms such as lupus and the avian variety 



