118 ANNUAL REPORT OF THE Off. Doc. 



The wl)itt' areas in the kidney described above show a round-cell 

 infiltration and large numbers of tubercle bacilli. The bronchial 

 gland« show areas of beginning caseation, a few giant cells, and in- 

 numerable tubercle bacilli. 



This calf showed a well-marked tuberculosis, proving that the cul- 

 ture with which it was inoculated had a degree of virulence above 

 that usuall}- found in cultures of human origin. Our experience with 

 this culture leads us to believe that the usual method of employ- 

 ing only guinea-pigs and rabbits in testing the virulence of the tu- 

 bercle bacillus does not always give entirely conclusive results. Un- 

 fortunately, the expense attending the use of larger animals hinders 

 th<Mr more general employment. 



History of Culture U. — Obtained from a child, aged three years, 

 whose death was due to tubercular meningitis. Autopsy: Lungs and 

 bronchial lymphatic glands full of miliary tubercles. Anterior 

 mediastinal gland.'^ much enlarged. Spleen extensively involved, 

 liver less so. On the abdominal surface of the diaphragm were a 

 number of flat, yellow nodules. Mesenteric glands enlarged, and 

 contained old, yellow, cheesy nodules. One small tubercle found in 

 the right suprarenal. Purulent and cheesy nodules found in meninges 

 and encephalon. The cultures were obtained from the mesenteric 

 glands. 



The pathologist. Dr. Hand, was unable to decide with certainty 

 as to the origin of this case. 



Increase of Yirulence hy Siiccessive Passage tlirongli Calves. — 

 In another experiment instituted by Dr. Leonard Pearson we have 

 proved that a typical tuberculosis can be produced in young cattle 

 by large and repeated doses of a human culture of moderate viru- 

 lence; and what is even more interesting and important, by succes- 

 sive passages through calves we have succeeded in bringing about a 

 marked increase in the virulence of this culture. The culture em- 

 ployed was isolated from human sputum in September, 1899, and is 

 designated "M." The animals were inoculated at intervals of a 

 week, the amount of culture being divided into four equal portions, 

 which were injected into the jugular vein, the lung, the peritoneal 

 cavity, and under the skin. Each week the dose was increased by 

 10 c.c. 



Two calves were infected in this manner, Nos. 26.562 and 26563. 

 With the tissues of No. 26562 the serial inoculations were begun, the 

 details of which, with the postmortem examination of the animals, 

 is given below. The result is shown in the following table: 



