THE ZYSINS. 149 



erated on -the addition of the serum of a normal guinea-pig. In this 

 connection some very interesting observations are recorded. A 

 guinea-pig whose blood contains a toxin which is markedly toxic to 

 its own spermatozoa m vitro, has spermatozoa which are quite as 

 motile as those of a normal animal and which when introduced into 

 physiologieal salt solution live for a long time ; however, if these 

 spermatozoa be placed in the serum of a normal guinea-pig they die 

 within from ten to twenty minutes, while the spermatozoids of a 

 normal guinea-pig live in the serum of another normal pig for many 

 hours. It is evident from these observations that these spermatozoa 

 have been acted upon by the sensitizer circulating in the blood of 

 the guinea-pig, but they are not killed by the autotoxin of the animal 

 because the blood does not contain a free alexin, this factor existing 

 only in the interior of the leucocytes. This explains why autotoxins 

 are active in vitro but inactive in vivo. The cellular elements are 

 destroyed in the serum in vitro and therefore this fluid contains both 

 the sensitizer and the alexin in the free state ; while in the living 

 organism all the cellular elements are intact, and the alexins are held 

 within the leucocytes, the sensitizer only circulating in the blood and 

 fixing itself to the spermatozoa in the living animal. This view is 

 supported by the following observation : If one injects into the peri- 

 toneal cavity of a guinea-pig, whose blood is autotoxic, living sper- 

 matozoa suspended in physiological salt solution, and examines the 

 peritoneal exudate during the next five minutes, it will be seen that 

 immediately after the injection there is a rapid phagolysis and that 

 the spermatozoa do not die until the leucocytes break down, after 

 which they are almost instantly killed. The picture is wholly dif- 

 ferent, if the same guinea-pig be treated with an injection of physio- 

 logical salt solution or a small quantity of leucotoxic serum. In 

 this case the phagolysis is very insignificant after the injection of the 

 living spermatozoids into the cavity. Phagocytosis is established 

 very rapidly and soon the spermatozoids while still alive are seized 

 upon by leucocytes. Attempts were made by Metalnikoff to obtain 

 an anti-auto-spermotoxin but without results. 



Metschnikoff' has succeeded, by inoculating guinea-pigs with 

 emulsions of the spleen and mesenteric glands of rats, in obtaining 

 from the former a serum which agglutinates and dissolves the leu- 

 cocytes of the latter. The active agent in sera thus prepared is 

 known as a leucolysin. Funck ^ has produced leucolytic sera by 

 treating guinea-pigs with emulsions of the spleens of rabbits. He 

 began by injecting half a spleen at a time, rubbed up in physiological 

 salt solution. After from eight to ten days the injection was re- 

 peated. From the animals thus treated he obtained sera which dis- 

 solved leucocytes both in vitro and in vivo. The alterations brought 



' Annates de I'Institut Pasteur, 1899. 

 ' CentralblaUf. Bakteriologie, 27. 



