452 FAMILY: TRYPANOSOMID^ 



by Franke (1905) in the case of the serum of cattle recovered from 

 T. brucei infections. Laveran and Mesnil (1900a, 1901a) first demonstrated 

 the agglutinating action of the serum of recovered rats on T. leivisi. 

 When the serum is allowed to act upon the tryj3anosomes in vitro, they 

 become arranged in clusters or rosettes with their flagellar ends directed 

 outwards (Fig. 152, A). Though the trypanosomes are attached to one 

 another by their posterior ends, there is no loss of activity, as evidenced 

 by the continued movement of the flagella. After some time the cluster 

 breaks up, and the individual trypanosomes swim away. The pheno- 

 menon is often termed " agglomeration " to distinguish it from bacterial 

 agglutination, which involves loss of vitality of the individual bacteria, 

 there being no tendency for the clumps to break up. 



Laveran and Mesnil (1901a) also found that if T. lewisi were injected 

 into the peritoneal cavity of rats which had recovered from an infection, 

 the trypanosomes quickly became attached to leucocytes, while no such 

 attachment occurred in the case of rats not previously infected. This 

 observation was extended to other trypanosomes by Mesnil and Brimont 

 (1908, 1909), while Levaditi and Mutermilch (1910) studied it in detail. 

 The last observers found that the reaction depended on immune sub- 

 stances in the blood of recovered animals, for the addition of immune 

 serum from these recovered animals to a mixture of trypanosomes and 

 cells obtained from artificially produced peritoneal exudate caused the 

 trypanosomes to become attached to the cells. The serum still retained 

 this power even after heating. This reaction, though in certain cases 

 quite specific, is too inconstant to be relied upon as a means of differentiat- 

 ing trypanosomes. 



Many experiments have been made to test the deviation or fixation 

 of complement in trypanosome infections with a view to diagnosis, but 

 the results so far obtained are very discordant. Sometimes, however, 

 definite and uniform results are obtained, as in the work of Watson (1915), 

 and Woods and Morris (1918) on infections of horses with T. equiperdmn. 

 Woods and Morris, working with dogs, found that, using as antigen a 

 salt solution of the spleen of a heavily infected animal, complement 

 fixation usually followed, but sometimes occurred before, the appear- 

 ance of trypanosomes in the blood of the dog. The reaction, however, 

 always appeared before clinical manifestations of disease. Therapeutic 

 injections of arsenobenzol into infected dogs not only caused the try- 

 panosomes and clinical symptoms to disappear, but so altered the 

 serum that the complement fixation test became negative, as in normal 

 dogs. 



The complement fixation test has been employed on a large scale for 

 diagnostic purposes in the case of dourine of horses in Canada. The 



