92G EXPERIMENT STATION RECORD. 



second injection but bad not to subsequent ones, ext(;nsive tuberculosis 

 was found wbicli was certainly of old standing, for, witb tbe exception 

 of tliose in tbe tboracic glands, tbe tubercles were surrounded by an 

 unusually dense coat of connective tissue. 



"The more this matter is iuvestigated the greater must the couviction become 

 that if we are to use the Koch test for purposes of eradicating tuberculosis from 

 among the cattle of the country, we have a more difficult task before us than is 

 tisually believed by cxpoueuts of the tuT)erculin test. We need to proceed with 

 greater care and less confidence. It re<iiiires heroic measures and patience in their 

 application. Eradication can not be rapidly nor easily effected." 



Further experiments with an attenuated tuberculosis bacillus, 



A. E. DE ScHWEiNiTZ and E. C. Schroeder ( U. S. Dept. Agr., Bureau 

 of Animal Industry Bui. 13, pp. 11-14). — An account is given of experi- 

 ments witb attenuated tuberculosis bacillus upon a monkey and 18 

 guinea pigs. Th.e monkej^ received inoculations of tubercle cultures, 

 thirtieth and tliirty-secoud generations, and lived months. Death 

 occurred from natural causes, and jiost-mortem examination revealed no 

 signs of tuberculosis. Similar results followed inoculation of guinea 

 pigs. The authors conclude that their experiments "have proved con- 

 clusively the attenuated character of this germ. Although this germ 

 is so attenuated and innocuous to animals, its ability to grow in arti- 

 ficial media is tis good and better than ever, and the tuberculin obtained 

 from its culture is as satisfactory as that prepared from a more virulent 

 germ.'' 



The grow^th of the tuberculosis bacillus upon acid media, E. A. 

 DE ScHWEiNiTZ and M. Dorset ( U. >S'. l>ept. Af/r., Bureau of Animal 

 IwluHiry Bui. 13,2)p. 7-10, ph. 2). — The authors find that the bacillus 

 cultures will grow upon meat broth of an acidity requiring the addi- 

 tion of 21.6 cc. decinormal sodium hj'drate solution to neutralize 100 

 cc. of the media; upon artificial media requiring -IS cc. of sodium 

 hydrate solution for neutralization; and upon the acid beef broth and 

 acid artificial media to which from 1 to 3 per cent of one-half normal 

 hydrochloric acid has been added. After the growth of the tuber- 

 culosis germ upon the media described is well advanced and apparently 

 has ceased, the acid reaction of the cultures is still more marked. The 

 growth of the germs and their morphological changes as observed by 

 the authors differ from those reported by other investigators. Plates 

 are given showing the appearance of the growth upon ditferent media. 

 The authois believe certain changes in the morphology of the germ 

 indicate the presence of heteromorphic forms of the tuberculosis bacil- 

 lus and a genuine pleomorphism caused by the changed conditions of 

 bfe. 



"If the germ is transferred from an acid culture after it has been cultivated on 

 acid media for a number of months to a neutral nutrient Huid it will no longer grow. 

 There would seem from this to be proljably a poisonous principle secreted by the 

 germ. It may be a true acid or, more likely, a substance with an acid reaction. In 

 the experiment, as the germs used for inoculation still doated ou the surface of the 



