No. 7. DEPARTMENT OF AGRICULTURE. »1 



to age, size, weight and condition. One of these lots was subdivided 

 into two groups of three each. 



The three cai'ves of one of the sub-groups were given seven intra- 

 venous injections of a standard suspension^ in water of tubercle ba- 

 cilli of human type (culture M). The dosage began at 1 c. c. and was 

 increased to 6 c. c. The intervals between injections were from six 

 to twenty days, and the period covered was from February 9 to May 

 1, 1903, as is shown by the protocols. These same calves received 

 another and final intravenous injection of 5 c. c. of a standard sus- 

 pension of living tubercle bacilli (culture M) about a year later, March 

 29, 1904. 



The three calves of the second sub-group were given subcutaneous 

 ijijectious of tuberculin at intervals of from two to ten days. The 

 injections of tuberculin were repeated until the hypersensitiveness 

 of the animal to tuberculin had disappeared, after which the calves 

 received an intravenous injection of a suspension of tubercle bacilli 

 (culture M) in water. Following each intravenous injection of liv- 

 ing tubercle bacilli, the animal was again given tuberculin a num- 

 ber of times until its hypersensitiveness to tuberculin again disap- 

 peared. The procedure in these cases in respect to the order of the 

 injections of tuberculin bacilli was as follows: Two subcutaneous 

 injections of tuberculin, an intravenous injection of tubercle bacilli, 

 six injections of tuberculin, an injection of tubercle bacilli, six 

 injection of tuberculin, an injection of tubercle bacilli, three 

 injections of tuberculin. The period of treatment extended from 

 T'ebruary 9 to April 30, 1903, inclusive; the exact times of adminis- 

 tration and the doses are shown by the protocols. The calves of this 

 group, as of the first group described, were given an intravenous 

 injection of 5 c. c. of standard suspension of living tubercle bacilli 

 (culture M) March 29, 1904. Following this, tuberculin was adminis- 

 tered five times at intervals of three or four days. 



The remaining six calves were given no treatment whatever, but 

 were, at all times, kept with the six calves under treatment; so 

 that all of the twelve calves in this experiment were subjected to 

 the same conditions of life and subsisted upon the same kind and 

 quantity of food. 



All of the calves were kept in a stable until May 29, 1903, when 

 they were placed upon pasture, which became very scanty during the 

 latter part of the season. During the winter of 1903-4 the cattle 

 were fed mixed hay, corn fodder, and a grain mixture of bran and 

 corn meal. Only a little grain was fed. About the middle of May, 

 1904, the cattle (now about two years old) were again placed on pas- 

 ture, where they remained until they were killed at the close of the 

 experiment. 



Two cattle, both controls, died; the first one May 5, 1903; the sec- 

 ond September 13, 1904; two, one control and one treated, were killed 

 April 4, 1904, and the rest were killed in September, 1904. 



When the cattle in this experiment died or were killed they were 

 submitted to careful post-mortem examination. Material was stained 

 for examination for tubercle bacilli and guinea-pigs were inocu- 

 lated from the lesions of some of them. Histological examinations 



1 By a standard suspension is here meant a suspension of tubercle bacilli in water, in such 

 quantity as to give an opacity equal to that of a twenty-four-hour culture of typhoid bacilli 

 in bouillon; 1 c.c. of such a suspension is estimated to contain the equivalent of 0.0013 gram of 

 tubercle bacilli dried ten days In a desiccating chamber over calcium chloride. 



