86 ANNUAL. REPORT, OF THE UfC. i>u<; 



in the blood of apinials tliat have boon troatod with toxins havo been 

 used. Toxins of various kinds havo boon oniph)yed; from the orig- 

 inal and new tuberculin of Ivoch to Uie toxalbuinin, the watery tuber- 

 culin, the tubercle bacilli deprived of fat of Maragliano and bacillary 

 pulp. 



The antitoxins that have been used have been develojjed as a 

 result of the injection of the various toxins mentioned above, and also 

 living tubercle bacilli of low virulence. 



The reports of the therapeutic experiments made upon infected 

 animals with tuberculosis toxins and antitoxins are numerous, but 

 cannot be regarded as convincing. Most of these experiments have 

 been made upon rabbits and guinea-pigs. Neither rabbits nor guinea- 

 pigs are altogether satisfactory for experiments of this kind; the 

 former because of their comparative immunity to tubercle bacilli 

 of the human type, the latter on account of their excessive vulnera- 

 bility to inoculation tuberculosis of either of the mammalian types. 

 Enough work has been done to denote that the progress of a tulDor- 

 culous infection may be controlled in some degree by specific means. 

 It is important that these various methods shall be compared and 

 measured both quantitatively and qualitatively. There is here a large 

 and important field of labor for the critical experimentalist. 



Among the means that have been proposed for controlling the 

 spread of tuberculosis among cattle is vaccination, or the inoculation 

 of animals with living cultures of tubercle bacilli of low virulence 

 for the animals upon which they are inoculated. This method of 

 producing artificial immunity has been the subject of considerable 

 study both in this country and in Europe, and has been reported upon 

 to this society by the writers of this paper. 



In connection with some tuberculosis vaccination experiments 

 made by the writers, the opportunity occurred to test the effect 

 of vaccination upon some young cattle already infected with tuber- 

 culosis. As this treatment appears to have had a decided effect upon 

 the course of the disease in the infected animals treated, it is con- 

 sidered that our observations should be placed upon record, espe- 

 cially since the work covered nearly two jj^ears, long enough to show 

 definite results, and is the first of the sort of which we have knowl- 

 edge. 



In testing with tuberculin a large herd of shorthorn and grade 

 shorthorn cattle in December, 1902, that ^^as known to have been 

 infected with tuberculosis for a number of years, it was found that 

 practically all of the members of the herd responded affirmatively 

 to the test. Among the animals so responding were twelve calves 

 from six to eight months old. As these calves had mingled rather 

 freelv with the members of the herd, and as thev had been reared 

 on the milk of extensively tuberculosis cows, it w'as not surprising 

 to find that they responded to the tuberculin test. These twelve 

 calves were obtained for use in this experiment. They were shipped 

 to Philadelphia and were placed in a temporary building on the 

 grounds of the veterinary school, where they were kept apart from 

 other cattle. 



The twelve calves were again tested with tuberculin February 2, 

 3, 1903. All responded to this test. They were then w^eighed and 

 divided into two lots of six each, as nearly equal as possible in respect 



