lOK'J YKTKKIXAKY BfEDIOIKB. 681 



result of experimental work in which various species of animals are used, is 

 baaed on the toxicity of tuberculin for tuberculous animals and is a modification 

 of the standardization test originally defined and used by Koch. 



Guinea pigs, practically alike in size, age, and weight, are Infected with 

 tuberculosis through the subcutaneous Injection of tuberculous material pre- 

 pared by making a suspension in Sterile, distilled water of fresh, tuberculous 



guinea pig tissue. Tins is filtered through ordinary filter paper, and the filtrate 

 used in amounts depending upon its concentration of tubercle bacilli as deter- 

 mined microscopically. Material of this nature is considered preferable to sus- 

 pensions made wilh pure cultures, as a more even distribution of tubercle bacilli 

 is obtained and the dangers of anaphylaxis from foreign proteins are eliminated. 



In about three weeks after the guinea pigs have been infected, inoculation 

 tests with a standard tuberculin are made to determine the degree of sensitive- 

 ness to tuberculin. The animals are considered ready for the practical tests on 

 the day when one cattle dose of standard tuberculin per r,(M> gm. weight causes 

 death within 24 hours. The average length of time required to produce this 

 degree of sensitiveness is about -'.) days. 



It is necessary that any sample of tuberculin, in order to possess a reliable 

 degree of potency, should kill within 24 hours at least half of the group of 

 six sensitized guinea pigs injected with it, and that normal guinea piu r s 

 injected with it should be alive and well at the end of 24 hours. All animals 

 that die must show on autopsy the characteristic lesions found when tuber- 

 culous animals die as the result of an injection of tuberculin. The normal 

 guinea pigs are kept under observation a .sufficient length of time for tuber- 

 culosis to develop in case the tuberculin happens to be contaminated with living 

 tubercle bacilli. 



The authors state that a superpotent tuberculin (provided it does not injure 

 healthy guinea pigs injected with it) is greatly to be preferred to a tuberculin 

 of subnormal potency. 



Tuberculosis eradication, J. A. Kikuxan (Anicr. Jour. Vet. MetL, I \ (1919), 

 No. 8, pp. 103-111). — A paper presented at the annual meeting of the U. S. 

 lave Stock Sanitary Association, held in Chicago in December, 1918. 



Tuberculosis and our live-stock industry. J. A. Kierxan (Jour. Anirr. Vet. 

 Med. Assoc, 5/ t (19 IS), \o. 2. pp. 107-120. 



The connection of milksickness with the poisonous qualities of white 

 snakeroot (Eupatoriurn urticasfolium), W. G. Sackktt (Jour. Infect. Diseases, 

 2h (1919), No. 3, pp. 231-259).—" Both the fresh, green /:. urliro folium and the 

 dried leaf powder contain an active ingredient which is poisonous for rabbits. 

 The active poisonous principle is present in plants grown In the greenhouse, 

 as well as under natural out-of-door conditions." The active constituent is solu- 

 ble in 95 per cent alcohol, and in a mixture of ether-chloroform and ammonia, 

 and in each case its solution yields a solid extract on evaporation which is 

 poisonous for rabbits but not for guinea pigs. The active ingredient is not 

 yielded by extraction with physiologic salt solution. It is present in the 

 leaves, but not, or only sparingly so, In the stems and roots of dried plants. 



"There is no Indication of anaphylaxis. So far as is shown by these experi- 

 ments, neither the leaf powder nor the different extracts are poisonous for 

 guinea pigs. The viscera and meat, from rabbits which had died from Eupa- 

 toriurn poisoning, when fed to a cat were without harmful action. 



" No difference in poisonous properties could be noted between plants from a 

 * milkslck ' and ' nonmllkslck ' area. The fatal dose of the leaf powder differs 

 with the different animals, ranging from 4 to 17 gm. ; whereas, the ether- 

 chloroform-ammonia extract from 16 gm. given in three doses 24 hours apart 

 Invariably caused death in 4 to G days. 



