234 CLINICAL DIAGNOSTICS. 



Results thus far have not been uniformly the same, but 

 are nearly as reliable as those obtained from the Subcutaneous 

 Method. The positive reactions are more trustworthy than the 

 negative. 



The Intracutaneous Method. 



On a smooth healthy portion of the side of the neck, lo- 

 cate two points separated by a distance of five centimeters. 

 These points should be marked for identification by clipping 

 the hair. Place the thumb and index finger of the left hand 

 on these points, draw the skin into a fold and ascertain the 

 thickness of the fold by means of a suitable instrument. 

 Qean the skin between the two points with alcohol, raise the 

 same into a longitudinal fold and then inject into the cutis 

 O. 1 cm. of a mixture of equal parts of tuberculin and normal 

 physiological salt solution. Use a graduated syringe and a 

 fine needle. 



If the swelling of the skin increases 0.3 cm. or more in 

 the course of twenty-four hours, the animal is to be regarded 

 as tuberculous. Slight swellings or premature swellings are 

 of doubtful significance. 



The cutaneous tuberculin test is not as reliable as either 

 of the foregoing. 



These so-called local tests are recommended when the 

 temperature of the animal is abnormally high or when varia- 

 tions occur or are suspected. Sometimes the application of 

 several methods is of value. The local tests may be applied 

 simultaneously and then followed by the subcutaneous. 



Inoculation of Experimental Animals. The milk of 

 tuberculous animals contains tubercle bacilli in all cases where 

 the udder is affected with tubercular processes ; frequently 

 also in the apparent absence of such processes. The udder 

 should be thoroughly milked, massaged and then again milked. 

 The last drawing of milk is centrifuged, the cream and sedi- 

 ment mixed and used for intraperitoneal injection. If tuber- 

 cle bacilli are present, tubercular nodules will develop on the 

 peritoneum (omentum), spleen and liver in the course of two 



