No. 6. DEPARTMENT OF AGRICULTURE. 145 



tubercle, the size of a pea aixl ( oiiiijletely calcified, in a mesenteric 

 gland. Two control cattle inoculated with an equal dose of the same 

 maierial died of generalized tuberculosis. Of the other three cattle 

 of (he series one was tubercular at the beginning of the experiment. 

 All of these were inoculated intravenously from seven to eleven times 

 during a period of from two to three years with emulsions of tuber- 

 culous materials and with cultures from various sources. It is in- 

 teresting to iiote that the first inoculation upon each of the cows 

 that was free from tuberculosis at the beginning of the experiment 

 was made with avian material which was probably of very low viru- 

 lence for cattle. The cattle so inoculated died of tuberculosis after 

 two to three years from the beginning of the experiment, and in each 

 case the chief lesions were in the kidneys aud the brain or its cover- 

 ing membranes. The cerebral lesion appears to have been the imme- 

 diate cause of death in each instance. There can be no doubt that 

 thes animals were remarkably resistant to tuberculosis, because they 

 lived for months or years after repeated inoculations with large 

 quantities of material of proven virulence for cattle. 



Von Behring announced December 12, 1901, thaf he was engaged 

 in studying the immunization of cattle against tuberculosis, and he 

 has since published a report (Beitrage zur Experimentellen Ther- 

 apie, ITeft 5, 1902) upon his work. He details experiments upon sev- 

 eral cattle treated with injections of tuberculin and with cultures 

 of varying degrees of virulence and from several sources, and also 

 inoculated with tuberculous material or cultures of proven virulence. 

 It may be noted that a pure culture virulemt for cattle was not avail- 

 able for use in von Behring's work until 1901. The experiments 

 upon seven cows specially reported were commenced between July 

 and December, 1901. These cows have all received repeated injec- 

 tions of tuberculin and of tubercle virus of low and high virulence. 

 All of the protected cows are still alive excepting ooe that was killed 

 and was found to have numerous tubercular nodules in the lungs, 

 although these were believed to be retrogressive. This general ex- 

 periment cannot be looked upon as finished, and any report upon it 

 must be regarded as incomplete until the cows die or are killed and 

 ai'e examined post-mortem. The cows may appear to be io good 

 health now, but notwithstanding, they may be extensively tubercular. 

 However, that they are alive after receiving quantities of virulent 

 tuberculous material that are sufficient to kill untreated cows shows 

 that they have extraordinary resistance to tuberculosis. The 

 method used to treat these cows was not systematic nor the one that 

 he now recommends upon the evidence of experimeuts not j'et pub- 

 lished. The method now recommended by him is to inject intra- 



10—6—1902 



