WILLIAM H. TALIAFERRO 



687 



injected into mice infected with the passage strain of organisms, an artificial crisis 

 should follow similar to that seen in the natural infection in the guinea pig. Strange 

 to say, most earlier investigators failed to obtain such results. Thus, Massaglia (1907) 

 failed to increase the length of life of mice infected with T. evansi over that of a con- 

 trol with the injection of 1.0-2.0 cc. of serum from guinea pigs during a crisis. Diesing 

 (1905), however, reports the temporary disappearance of parasites and clinical im- 

 provement of cattle and horses receiving serum from asses after recovery. Kleine 

 and Mollers (1906) produced artificial crises in mice infected with T. togolense. Re- 

 cently, the author and Johnson (1926) working with T. equinum have been able to 

 produce artificial crises in mice infected with the passage strain by injecting lytic 



12 w I a 



DaijS afier |p|9Ciion 



10 1? W 



Fig. 6. — Production of an artificial crisis in a mouse with serum taken from a guinea pig after a 

 natural crisis. Tlie first graph shows tlie course of the infection in the guinea pig and the time of 

 bleeding for immune serum. The second graph shows tlie crisis resulting from a dose of 0.3 cc. of the 

 guinea-pig serum and the relapse which followed. The third graph shows the course of the infection 

 in the untreated control mouse. 



serum obtained from guinea pigs and rabbits after a trypanolytic crisis, from a sheep 

 during its chronic infection, and from mice after incomplete cure with drugs. Figure 

 6 shows an experiment in which lytic guinea pig serum was used. Following infection 

 with the passage strain and a crisis, the guinea pig (first part of figure) was bled and 

 its serum preserved on ice until ready for use. In the meantime two mice had been 

 infected with the same strain, and when the parasites showed up, one (second part 

 of figure) was injected with 0.3 cc. of the guinea pig serum while the other (third part 

 of figure) was left untreated as a control. Within an hour no trypanosomes could be 

 found in the experimental mouse, nor did they reappear for six days. On the follow- 

 ing day they were found in small numbers, and thereafter increased steadily until 

 the animal died. In marked contrast the control mouse showed an uninterrupted 

 increase of parasites until its death on the sixth day. Thus, an injection of 0.3 cc. of 

 immune (lytic) serum not only produced a six-day crisis but prolonged the mouse's 

 life seven davs over that of the control. 



