BUREAU OF ANIMAL INDUSTRY. 361 



thus indicating that the complement fixation in trypanosome affec- 

 tions represents a group reaction. Knowing the great abundance of 

 trypanosomes in experimental rats aflFected with surra, a culture of 

 1'ry'i>anosoma eransi was obtained through the courtesy of Prof. 

 Novy, of the University of Michigan, and injected into a number of 

 white rats. After four or five days, when the disease was at its 

 height, the rats were bled to death, and as an antigen a shake ex- 

 Iract was prepared from the blood and the macerated spleen. The 

 preliminary tests with this antigen were very encouraging, as the 

 sera of the dourine horses at the Bethesda Experiment Station and 

 the sera of surra rabbits during both the febrile and afebrile periods 

 gave in all instances excellent fixation. 



The smallest quantity of dourine serum which ^ave a positive 

 reaction proved to be 0.05 cubic centimeter; the positive tests showed 

 that even a fixation in 0.2 cubic centimeter of serum is sufficient for 

 diagnostic purposes. Sera from normal animals, also those affected 

 with various other diseases, failed to give a reaction. Incidentally it 

 ma}^ be mentioned that the sera from three swamp-fever cases were 

 tested with negative results, thus further proving that the cause of 

 that disease is not a trypanosome. The antigen was used in dilutions 

 of 1 to 10 and retained its ofFectiveness for three months after its 

 preparation. The ease with which an affirmative diagnosis of dourine 

 may be obtained with this test is not to be compared with the arduous 

 task which is necessary to determine the presence of the causative 

 trypanosomes microscopically. 



The possibility of utilizing the complement-fixation test for the 

 diagnosis of dourine is of great moment in the control of the disease. 

 By this means it is possible to determine all infected animals witliin 

 a short time and dispose of them by methods best suited for the 

 control of the disease. Furthermore, the introduction of the dis- 

 ease into the country could also be guarded against by a compulsory 

 requirement of this test on all horses imported from countries in 

 which dourine is present. 



Since the foregoing was written the value of this method of 

 diagnosis for dourine has been well illustrated. Late in June Dr. 

 Knowles, State veterinarian of Montana, wrote the bureau to the 

 effect that there were suspicious cases of dourine in eastern Montana, 

 and requested that an expert be detailed to make a diagnosis. Owing 

 to the impossibility of complying with this request a telegram was 

 forwarded asking for blood sera from the suspected animals. This 

 arrived on July 22 in excellent condition, and on the following day 

 the complement-fixation test showed that four of the five samples 

 gave a positive reaction. 



GLANDERS. 



The determination of occult and Intent cases of glanders in horses 

 and the necessity of an early diagnosis in these animals are of great 

 importance, and therefore experiments have been conducted on an ex- 

 tensive scale in many laboratories in order to determine the most reli- 

 able method by which such cases may be diagnosed. Following the 

 splendid results which were obtained in Germany by the combined 

 complement-fixation and agiilutination tests for the diagnosis of 

 glanders, this method has been adopted by many laboratory workers 



