312 ANNUAL REPORT OF THE Off. Doo. 



tuberculous organs of man and cattle, and that (he two sets of ani- 

 mals would U"3id themselves to an interesting comparison, besides 

 fuUilling the primary object of comparing the virulence of human and 

 bovine material. 



The plan was carried out for the bovine material, but failed for 

 the lunnaei, as all the guinea pigs died within forty-eight hours after 

 inoculation. Tlie second series of animals were inoculated with 

 human material from another source and obtained at a later date. 

 The results, while «ot entirely comparable, are nevertheless inter- 

 esting and valuable. 



Objections in Cuc of Ttiberciolous Material. — There are several dis- 

 advantages in using tuberculous material which were not over- 

 looked in planning tliis work. (1) It is impossible to give accurate 

 doses, for although our suspeiisions may be made of an equal opacity, 

 jind counts of etpaal amounts show approximately the same number 

 of ba( illi, there is no way of determining what proportion of these 

 bacilli are capable of multiplication. (2) Material from man almost 

 alw'ays contains other bacteria. Our knowledge of mixed infections 

 is too gcant to enable us to estimate the part played by those other 

 species in determining the result; whether they inhibit or aid the 

 action of the tubercle bacillus. The same is true of bovine material, 

 although to a less extent, the tuberculous foci being more apt to re- 

 main inclosed. On the other hand, infection under natural condi- 

 tions is always through such mixed material, and this method of 

 inoculation approaches in some degree the conditions we meet in 

 practice. 



Source of Bovine Tuberculous Material. — The bovine tuberculous 

 material was obtained from a cow six years old, which had shown 

 symptoms of tuberculosis for a long time, and was finally condemned 

 and killed. She showed, postmortem, a generalized involvement of 

 the thoracic cavity with some invasion of the abdominal organs. In 

 the lungs but little tissue approaching normal was found, and the 

 pleurae were studded with small nodules. Many of the tuberculous 

 areas in the lungs had undergone caseation. The mediastinal 

 glands were enormously enlarged and caseous. Scattered over the 

 ptjritoneum were many nodules. The liver was considerably in 

 volved, and the portal and mesenteric glands were enlarged and 

 caseous. Other abdominal organs showed no macroscopic lesions. 

 Nodules were taken from the pericardium, mediastinal and mesen- 

 teric glands, lung and pleura. After thorough trituration in a mor- 

 tar, each part sei)arately, they were mixed, sterile water added, and 

 the whole strained through cheese-cloth. With this material a 

 series of animals was inoculated, and at the same time a number of 

 guinea-pigs. These all contrncted tuberculosis, four dying on the 

 fifteenth day. Portions of their organs were prepared in the same 



