EXPERIMENT STATION REPORTS. 259 



Third : If the artificial cultivation experiments should be successful, 

 then we would have an excellent basis for a rational vaccine treatment 

 for h6g cliolora. Such a treatment, with the more or less permanent 

 immunity usually obtained in such treatment, is to be distinguished 

 from the Dorset-Niles protective serum and the resultant very tempo- 

 rary, passive immunity secured with serum-alone treatment. 



Fourth: With the perfeclion of a method of complement fixation, as 

 noted under Experiment 2, there is a possil)ility of working out a cheap 

 and quick method of standardizing the Dorset-Mies serum. Just at 

 present this is the greatest improvement that can be hoped for in the 

 Dorset-Niles treatment. 



While no final report on any part of the work is j-et desirable, some 

 points may be worth touching upon. 



The cultivation experiments, — by no means complete as yet, — were 

 carried out with samples of virus defibrinated blood, virus serum ffrom 

 clotted blood) and virus salt solution obtained by the method of Eob- 

 bins and of Craig. These solutions were filtered, in dilutions of 1 to 3 

 with normal salt solution, through Pasteur-Chamberland and Buchner 

 filters. Bacterial sterility was. proven by inoculation tests in the ordi- 

 nary media, and then attempts vrere made to cultivate the virus on 

 various special media, under aerobic and anaerobic conditions, and at 

 various temperatures. 



The virus salt solution proves the easiest to handle, because of many 

 difficulties encountered in filtering the blood samples. No definite re- 

 sults can be reported, but the tests at different temperatures will be car- 

 ried out more completely another year. 



In the endeavor to apply the method of complement fixation to the 

 early diagnosis of hog cholera, various extracts were tested for antigenic 

 properties, using immune, hyperimmune and virus sera for specific am- 

 boceptor. This is a reversal of the ordinary complement fixation technic 

 and takes for granted that if the method is applicable at all, these sera 

 should contain such a specific lytic amboceptor for the specific virus of 

 hog cholera. 



Various extracts of diseased organs from hog cholera animals were 

 used. Some definite results were obtained with such organ extracts, but 

 the fact that almost invariably such organs are contaminated with B. 

 cholerae suis, renders this work uncertain. Using a pure culture of this 

 organism it is possible to obtain complement fixation with some samples 

 of hyperimmune sera. 



It seems probable that the most definite results will be obtained with 

 an antigen prepared from virus salt solution. This fluid can be obtained 

 free from B. cholei'ae siiis contamination, is powerfully virulent for sus- 

 ceptible hogs and a concentrated salt virus should contain enough of the 

 specific virus to give antigenic properties. The results here are promis- 

 ing but not complete. 



It is necessary to have enlarged facilities for experimental animals to 

 carry out this work at all satisfactorily and the new building now being 

 erected will soon render this possible. 



Another problem taken up during the year was that of white diarrhea 

 in chicks. This disease was first studied in the eastern states about ten 

 years ago and has been the subject of extensive reports from the New 



