144 VERMONT AGRICULTURAL REPORT. 



turn was thrown regularly into the pond occupied by the carp. 

 The germ isolated iroin the carp grew at a very much lower 

 temperature than the human germ, but its origin was undoubt- 

 edly human. All this work has proven very conclusively that 

 the tubercle bacillus found in different animals may adapt itself 

 very readily to different surroundings, may be accustomed to 

 grow at lower or higher temperatures, and may eventually grow 

 under conditions that would have been originally entirely de- 

 structive to it. This latter point has been very practically 

 demonstrated in this laboratory, the experiments showing that 

 the tubercle bacillus can be gradually accustomed to a nutrient 

 liquid containing glycerin, sodium and potassium phosphate, 

 and ammonium phosphate. When obtained directly from the 

 animal the germ will not grow on this solution, but by cultivat- 

 ing it first upon a medium which more nearly produces the con- 

 ditions that the germ finds in the animal body it can then be 

 transferred to the solution of mineral salts and caused to grow 

 rapidly and in great abundance. If such conditions can be 

 produced artificially outside of the body there is certainly every 

 reason to believe that the germ can very readily adapt itself to 

 changes in temperature and nutrient conditions that are found 

 in the bodies of different animals and still cause tuberculosis. 



During the seven years that tuberculin has been prepared in 

 this laboratory for distribution by the Bureau of Animal In- 

 dustry to various State officials and experiment stations, the 

 results have been very generally satisfactory. Thousands of 

 reports have been received, from nearly every State in the 

 Union, from Canada and the West Indies, and from many dif- 

 ferent sources, and with one or two exceptions (exceptions 

 arising very probably from the fact that the users of the mate- 

 rial were not experienced in handling it) all have realized the 

 importance and usefulness of tuberculin. 



There have been one or two cases in which it was claimed 

 that the tuberculin gave misleading results. One may be noted 

 especially. A supply of tuberculin had been sent from this 

 laboratory in the spring of the year to a certain State veterina- 

 rian who distributed it to some of his assistants. One of these 

 assistants kept the bottles standing in his office for several 

 months in the hot sun. He then used some of their contents 

 to test an animal, which, according to report, passed the test 

 and was sold. Subsequently, with another lot of tuberculin, 

 the animal showed the tuberculin reaction, which diagnosis was 

 proved upon post-mortem examination. The doctor to whom 

 this tuberculin had been sent was requested to forward the bot- 

 tle from which the material had been used to this laboratory. 

 He said that he could not get this, but sent another bottle from 

 the same lot which had not been opened but kept under the 



