52 TUBKKCULIN, ITS HISTOIJY, PREPARATION AND USE. 



his £10, wends his way homeward with his purchase, perfectly 

 satisfied that he has a bargain in the animal which, in his 

 opinion, is free from tuberculosis. 



Case II. — Mr. C is anxious to buy a dairy cow for the 



purpose of supplying milk to his family. 



Mr. D , a breeder of dairy cattle, is also anxiotis to meet 



the requirements of Mr. C , and allows him to select any 



cow in his herd at a certain price. 



Accordingly Mr. C picks out a three-quarter bred 



Jersey cow, and as it is such a very quiet animal, he is desirous of 

 having it tested with tuberculin without further delay. 



The ever obliging Mr. D at once produces the clinical 



thermometer and two small stoppered bottles — one bearing the 

 characteristic label of Koch's tuberculin, and the other of 

 Bang's. 



Mr. C remarks " that as there is a great deal in a 



name, he prefers to use Koch's tuberculin;" consequently a definite 

 quantity of the contents of the bottle labeled ' ' Tuberculinum Kochii^' 

 is diluted with weak carbolic solution and injected into the selected 

 cow ; the records of the animal's temperature taken next day 

 indicate that no reaction has taken place. 



Mr. C then purchases what be conscientiously believes 



to be an animal which has been proved by the tuberculin test to- 

 be free from tuberculosis, and ever afterwards feels proud in 

 informing his numerous friends how very mnch better it is, 

 instead of having a limited quantity of inferior milk supplied by 

 a dirty careless milkman, to have, practically speaking, an 

 unlimited supply of pure fresh milk from his own cow, which, 

 he says, is guaranteed free from tiiberculosis from the fact that 

 it has passed the tuberculin test. 



Little does Mr. C imagine that although the stoppered 



bottles and labels are the genuine articles, the contents was cold 

 tea placed there intentionally by that courteous gentleman, Mr.. 



J) , who can rest assured that his cattle, whoever purchases 



them, will find no tuberculosis if tested with the tuberculin 

 which he generously supplies at the time oi purchase. 



