I04 AGRICULTURE OF MAINE. 



at the Vermont Experiment Station in the case of a cow which 

 was tested every six months for four or five years, and then 

 gave the largest milk and butter record ever got at the Station 

 from any cow, of any breed ; and during the experiments at 

 the Bureau of Animal Industry, Washington, D. C, over 

 3,000 c. c. of tuberculin were injected into a cow at intervals, 

 and the animal remained in perfect health at the close of the 

 year. If the living bacilli are not in the system, the amount 

 injected fails to make any impression whatever and is properly 

 eliminated. 



Among the objections which have been raised to its employ- 

 ment in cattle, but few of them will stand the test of scientific 

 investigation, and as experience in its use has brought a greater 

 measure of success, unfavorable reports are becoming rare, and 

 many who considered tuberculin unreliable are now acknowl- 

 edging that the fault was their own, and that conclusions had 

 been reached from far too restricted premises. 



A survey of the whole field shows, that if at the time of 

 testing, suitable aseptic precautions have been observed" the 

 animal is not in heat, or near parturition, and there is at the 

 time no concurrent disease, not two percent of cows will 

 react upon the first test unless tuberculosis is present, while 

 my convictions are daily being strengthened by practical work, 

 that no animal reacting under such conditions should ever be 

 released from quarantine, and again allowed to associate with 

 sound animals. I have encountered in my practice a few well 

 advanced cases of tuberculosis that absolutely refused to show 

 any reaction to tuberculin, where the system of the animal was 

 so thoroughly saturated with natural tuberculin that the slight 

 addition injected had no apparent eflfect, but such animals have 

 only been safely condemned by physical examination. 



The claim that in some cases cattle would react to tuberculin 

 where no tuberculosis could be found upon post-mortem, is 

 largely attributed to the crude and rough-shod manner of hold- 

 ing autopsies in barnyarrls or open fields where a thorough 

 search was often impossible. Often a few small tubercles at 

 the bifurcation of the trachea may be overlooked and Nocard 

 states that "There is a stage in the period of incubation when 

 it is too early for the tubercle to have been formed yet the 

 reaction shows the presence of the disease," but it is impossi- 

 ble to define that stage. Tuberculosis of the joints and bones 



