582 EXPERIMENT STATION EECOED. 



The diagnosis of contagious abortion in cattle by means of the comple- 

 ment fixation test, F. B. Hadley and B. A. Beach (Wisconsin Sta. Research 

 Bui. 24, pp. 217-248, pis. 4, figs. 2). — This bulletin concerns itself chieflj' with 

 the diagnostic methods for this disease, especially the complement fixation or 

 binding method. To determine the practicability of the complement fixation 

 test, the technique of which is described in detail, tests were carried out with 

 the sera obtained from about 500 animals. These animals were distributed in 

 widely separated herds, and were considered representative of the Wisconsin 

 dairy industry. 



" The accuracy of this method of diagnosis is as great as any method based 

 upon a biological reaction. Further experimentation may perhaps suggest some 

 modification of the present technique. Where large numbers of animals are to 

 be tested, such changes would be acceptable if not made at the expense of ac- 

 curacy. Howevei", at present we find it quite possible to run tests on 50 or 

 more animals a day without undue exertion. 



" The test affords a reliable means by which infected animals may be de- 

 tected. Proper methods of isolation and control may then be instituted by 

 which the disease can be prevented from spreading to noninfected cows and 

 heifers. It is a qualitative and not a quantitative test and simply indicates the 

 presence or absence of the specific immune bodies; but clinical history has so 

 closely corroborated the test that we may assume it to be a reliable guide as 

 to the presence or absence of the abortion bacilli." 



In order to determine if the test was rigidly accurate some additional ex- 

 periments were made with the station herd, which included heifers unavoidably 

 exposed to the infection and cows which were known to have aborted. The 

 test detected infected animals a long time before they aborted. It furthermore 

 showed that immune bodies were present longer than a year in some animals 

 and that they gradually disappeared in other cases. In the case of 1 calf, which 

 had dropped prematurely and was in constant association with infected animals, 

 the animal did not show immune bodies up to the time when she was a year 

 old. The serum of a herd bull, which associated with an infected cow, gave a 

 positive reaction. Bacteriological examinations of 20 placental membranes 

 were made with a result that 13 were found to contain the abortion bacillus. 



"The interpretation of the reaction may be summarized as follows: (1) 

 Cattle in which the serum shows a complete fixation of the complement in 

 quantities of 0.01 cc. and 0.02 cc. are or have been infected with abortion 

 bacilli. (2) Cattle in which the serum gives a complete complement fixation in 

 the quantity of 0.02 cc. and an incomplete fixation in 0.01 cc. amount, also are 

 or have been infected with the abortion bacilli. (3) Cattle in which 0.01 ce. 

 of the serum shows no binding while the larger quantity gives an incomplete 

 binding should be considered questionable reactors and retested after 4 to 6 

 weeks. (4) Cattle in which the serum shows no power of fixing the complement 

 in either amount should be considered free' from the infection." 



Freezing was not found to kill the organism, strongly binding antigens being 

 later prepared from the frozen strains, which were recovered in pure cultures. 



8ome field experiments with the test are also reported. 



Immunizing' tests in infectious intestinal catarrh, Miessneb and Kohl- 

 STOCK (Berlin. Ticrdrstl. Wchnschr., 28 (1912), ISfo. 23, pp. J, 50-1,52) .—T\iQ mate- 

 rial obtained by scraping the intestinal mucus membranes of bovines infected 

 with intestinal catarrh was rubbed up into a paste with commiuuted mesenteric 

 lymph glands in a mortar. A 20 per cent solution of antiformin was then 

 added, stirring constantly during the process, the mixture transferred to a 10 

 to 20 liter flask, and the flask with its contents shaken for 2 days in a shak- 

 ing device. The emulsion so produced was filtered and the filtrate ceutrifuged. 



