ACID-FAST GROUP 323 



rest upon quite different factors. The diagnosis of tuberculosis 

 in the human is generally accomplished by other means than in- 

 jection, on account of the severity of the reactions. In cattle it 

 may be relied upon quite implicitly if the test is carried out prop- 

 erly. 



Von Pirquet has described a cutaneous tuberculin reaction that 

 is of diagnostic value in man, particularly in young children. 

 The iimer side of the forearm is washed with ether. One drop 

 of old tuberculin is applied, and another at a distance of about 

 10 cm. The skin is slightly scarified and the drops rubbed with a 

 bit of cotton. A positive diagnosis is evidenced by the develop- 

 ment of a papule resembling that of vaccinia. The reaction is 

 quite local, showing that the tissues of the body distant from the 

 tuberculous lesions have been sensitized. The method has been 

 extensively tested and has been found quite accurate. Von 

 Pirquet secured positive reactions in 87 per cent, of the clinically 

 tubercular, in 20 per cent, of clinically tubercular free. The 

 reaction was found to be far more accurate during the first year 

 of life than later. Lignieres modified this method by shaving the 

 skin and avoiding scarification. Six drops of undiluted old tuber- 

 culin are applied and rubbed with a bit of absorbent cotton. The 

 reaction is similar to the preceding. It has been termed the anti- 

 tuberculin reaction. The intradermal method has yielded satis- 

 factory results when used upon cattle by some investigators; others 

 find it less reliable than subcutaneous injection. 



The ophthalmo-reaction of Calmette and the conjunctive^, reaction 

 of Wolff-Eisner have likewise found extensive use in recent years 

 in human diagnosis. A tuberculin specially prepared free from 

 gtycerin and other irritants is dropped into the conjunctival 

 sac. A positive reaction consists in the appearance of a pronounced 

 conjunctivitis, which shows itself in five or six hours and disappears 

 in two or three days. This reaction may be used upon cattle, but 

 it is not as specific as the subcutaneous injection. 



Transmission and Prophylaxis. Channels Through Which 

 the Organisms Leave the Body. These are determined largely in 

 both man and animals by the localization of the lesions. The 

 organism is to be found in the sputum in man and animals affected 

 by pulmonary tuberculosis. The infectious droplets thrown out 



