320 ANNUAL REPORT OF THE Off. Doc 



a series of exaininatioiis of material coughed up by cows, I failed 

 always (o lind bacilli of what has been described as the bovine type. 

 [•{I fact, the loujj^est tubercle bacilli I have ever observed, except in 

 old niltiiics, were seen in some specimens of this material. The 

 virulence of this material was greater considerably than human 

 sputum ordinaiily is, though the comparison was not made with 

 accuracy. 



Retention of Characteristics in Culture. — On blood-serum with 

 5 per cent, of glycerin, the tubercle bacillus from bovine sources, 

 will, as a rule, retain its morphological and cultural characteristics 

 for a long time. Culture H has now grown for two years (July G, 

 lUUl), and is of the sixteenth generation. Beyond an increased 

 vegetation, no marked change can be detected in it. With a single 

 exception (Culture F) the same may be said of all the cultures iso- 

 lated. This culture was isolated with some ditficultv, and so scant 

 was the growth for six generations that I was several times on the 

 poi«t of abandoning it. Only in the sixth generation was growth 

 enough obtained for experimental inoculation. Considerably more 

 growth took place in the seventh, and the eighth grew luxuriantly, 

 since which all sub-cultures have been abundant. From the eighth 

 generation on serum cultures were made on 5 per cent, glycerin agar, 

 and a« abundant growth obtained on this medium in the first trans- 

 fer. 



Co-incident with this increase of vegetative power came a marked 

 change in the morphology. From being short, thick and staining 

 evenly, it is now long, more slender than in the early growths and 

 shows marked beading. In other words, from being a typical 

 "bovine" culture, it has during the past ton months so changed that 

 it can now pass as a typical "human" culture. It will be observed, 

 by reference to Table IV, that its pathogenic power for guinea-pigs 

 and rabbits was not as great as is usually found in bovine cultures. 



Culture in djllodion Sacs. — The method of culture in the body of 

 jiving animals, which has been productive of such brilliant results in 

 the hands of the French, offers much assistance in the solution of 

 the inoblem before us. It has enabled Nocard' to demonstrate the 

 I)ossibiiity of so modifying the mammalian tubercle bacillus that it 

 becomes like the avian organism in culture and pathogenicity. We 

 are now atteini)ting to modify, two feebly virulent human cultures 

 by residence in the peritoneal cavity of cattle. 



Culture M was kept for seven months k\ the abdominal cavity of 

 a hciff-r. inclosed in collodion sacs, two sacs being used. On re- 

 moving tlie sacs but little multiplication of the bacilli was noted. 

 Cultures were recovered directly from the sacs. In the first trans- 

 fer the cultures grew more rapidly and abundantly than the original 

 culture, but the morphology of the individual bacilli cannot be said 

 to have changed (o a noticeable degree. The virulence was not in- 



