THE TUBERCLE BACILLUS 495 



cording to recent investigations, about 70 per cent of adults show a 

 positive reaction and in such cases it is probable that an old healed 

 tuberculosis may give rise to a positive test where absolutely no active 

 process exists. 



Recently, v. Pirquet has modified his procedure by using instead of 

 the 25 per cent solution given above, the pure, undiluted " Old Tuber- 

 culin." 



Moro^ has modified this by simply making a 50 per cent ointment of 

 tuberculin in lanolin and rubbing it into the skin without scarification. 

 It is more simple and equally efficient to massage into the skin a 

 drop of undiluted "Old Tuberculin." 



The Tuberculin Test as Applied to Cattle. — In cattle, the symptoms 

 of tuberculosis are not easily detected by methods of physical diag- 

 nosis until the disease has reached an advanced stage. In conse- 

 quence, cows may be elements of danger without appearing in any 

 way diseased to those who handle them. In consequence, routine 

 examination of herds by the tuberculin test has become one of 

 the necessary measures in public sanitation. According to Mohler,^ 

 an accurate diagnosis may be established in at least 97 per cent of the 

 cases. It is natural that a good deal of objection to the test is encoun- 

 tered on the part of dairy farmers and cattle raisers, and recently it has 

 been publicly claimed that the cattle are injured by the test. There is, 

 however, no scientific basis for this belief, if the test is carried out care- 

 fully and intelligently. As a matter of fact, the systematic use of the 

 test would eventually be distinctly advantageous to the owners of the 

 cattle themselves, since it has been shown that cows, even in the early 

 stages of the disease, may expel tubercle bacilli, either during respira- 

 tion or in the feces, and thus become a menace to healthy members of 

 the herd. 



The tuberculin test on cattle should be made as follows: (The 

 directions given below are taken directly from the circular sent out from 

 the Bureau of Animal Industry at Washington.) 



1. Begin to take the rectal temperature at 6 a.m., and take it every 

 two hours thereafter until midnight. 



2. Make the injection at midnight. 



3. Begin to take the temperature next morning at 6 a.m., and con- 

 tinue as on preceding day. 



To those who have large herds to examine, or are unable to give the 



1 Mm-a, Mtinch. med. Woch., 1906, p. 216. 



2 Mohler, Pub. H. and Mar. Hosp. Serv. Bull. 41, 1908. 



