No. 6. DEPARTMENT Oi<' AGKICUI^TURK. 287 



fiist to take up the sj&iematic stu(l> of the bacilli isolated iiom 

 various of the lower auimals and mau, and to call attentioii to cer- 

 tain fairly constant ditieieuces observed in the organisms from the 

 two sources which he considers sufficient to justify classifying them 

 as distinct varieties or races, though his experiments "show un- 

 mistakably the close relationship existing among the various cul- 

 tures studied."* 



Dr. K. K. Dinwiddle, ^ I'athologist and bacteriologist of the Ar- 

 kansas Agricultural Experiment Station (U. S. A)., has carded out 

 quite extensive experiments in which he has compared the viru- 

 lence of the human and bovine tubercle bacillus, and also human 

 tuberculous sputum with bovine material, for a number of the do- 

 mestic atiimals, his results showing a greater power for both the 

 bovine bacillus and material than for the human. 



The vast practical importance of the matter, no less than its 

 great scientific interest, was early realized by Dr. Leonard Pearson, 

 State Veterinarian of Pennsylvania, and under his direction we have 

 devoted much of our attention at the laboratory of the State Live 

 Stock Sanitary Board for more than two years past to the study of 

 the tubercle bacillus obtained from various cases of tuberculosis in 

 man and in cattle. 



In the carrying out of this work I have had throughout the effi- 

 cient assistance of Dr. S. H. Gilliland, on whom a large share of the 

 labor has fallen, and to whom is due much of the credit in its suc- 

 cessful issue. To him and to the several physicians who have in- 

 terested themselves in obtaining material for us, I beg to express 

 my obligation. During a considerable portion of the time that 

 Part II of the experiment was in progress. Dr. W. G. Shaw was in 

 charge of the animals, and did much of the work; while the bovine 

 material for the inoculations was obtained and prepared by Dr. J. 

 J. Repp, both of whom were at the time connected with the lab- 

 oratory. 



Our experimental work has been divided into two parts: 



1. Isolation and study of pure cultures from various sources in 

 man and cattle. 



2. Testing the pathogenic power of tuberculous material ot human 

 and bovine origine. ' 



1. Under the first division thirteen cultures, seven of human and 

 six of bovine origin, are included in this report. Of these, two 

 human and two bovine have been compared under conditions as 

 nearly identical tliroughout at it was possible to obtain them. Cul- 

 tures H (bovine) and K (human) were isolated within a few days 

 of each other, while L (bovine) and M (human) were made on the 

 same day. The first sub-cultures of both pairs were made on the 



