146 THE LYSINS. 



the serum of the immunized animal, no marked difference in the 

 action of these sera could be observed. In both instances the mo- 

 tility of the cells was arrested within from two to six minutes, when 

 the serum was fresh. (It will be noted that this observation is not 

 in accord with that reported by Metschnikoff.) The death of the 

 spermatozoa in the serum is not due to the fact that the latter does 

 not afford an adequate medium for the support of life, because the 

 same cells retain their motility for four hours when suspended in 

 physiological salt solution. Death is due to a toxic substance which 

 exists in the sera of both normal and treated animals. This was 

 shown to be the case by the following experiment : When ram's 

 spermatozoa were mixed with the serum of either normal rabbits or 

 immunized rabbits and the mixture allowed to stand for one hour at 

 37° and centrifuged, the supernatant fluid was found to have lost its 

 property of killing spermatozoa. A like result was obtained by 

 heating either normal serum or immune serum to 58°. However, 

 when immune serum was mixed with the ram's spermatozoa and the 

 mixture placed in the peritoneal cavity of a normal guinea-pig it was 

 found that the cells were more speedily killed than when a like ex- 

 periment was made using the serum of a normal rabbit. Both im- 

 mune and normal sera rendered inactive by heat were regenerated 

 when placed in the peritoneal cavity of guinea-pigs, but after being 

 thus regenerated, the immune serum acted much more intensely than 

 the normal serum. Both immune and normal sera were also ob- 

 served to agglutinate the spermatozoa, the former acting much more 

 promptly than the latter. It was also found that the immune serum 

 agglutinated the spermatozoa of the ram after these cells had been 

 deprived of life by being kept at a temperature of 58° for half an 

 hour, while normal serum did not have this effect. The serum of 

 the rabbit immunized against the spermatozoa of the ram did not 

 agglutinate the spermatozoa of the horse or bull and therefore the 

 reaction may be called a specific one. The serum of a rabbit im- 

 munized against the spermatozoa of the ram was found to have a 

 marked hemoljrtic effect on the blood corpuscles of the latter animal, 

 while it had no such effect upon the erythrocytes of the horse or ox. 

 The question arose as to whether the spermatocidal and the hemo- 

 lytic action of the immune serum were due to one or two substances. 

 In attempting to answer this question, it was found that when a 

 mixture of spermatozoa and erythrocytes from the ram was added to 

 the immune serum from the rabbit, the hemolytic action of the serum 

 was arrested. In another experiment it was ascertained that when 

 the immune serum was treated with an excess of spermatozoa and 

 the mixture allowed to stand for some time at 37°, then centrifuged, 

 the supernatant fluid had no hemolytic action. From these observa- 

 tions it was concluded that the spermatocidal and the hemolytic sub- 

 stance in the immune serum is one and the same substance, and that 



