HEMOLYTIC SERA AND THEIR ANTITOXINS. 189 



year ago we said that the modification of the corpuscle by the sen- 

 sitizing substance might be likened, as Fischer has done for diastases, 

 to a change in a lock so that keys that could not previously open it 

 were enabled to do so. In such a way certain alexins would "enter" 

 a sensitized corpuscle and destroy it; and other slightly different 

 alexins could not attack it. There must exist, then, certain suitable 

 relations between the sensitizing substance and the alexin em- 

 ployed in order to bring about a destruction of the corpuscles. We 

 shall not insist further on these conceptions, which have, indeed, 

 been made use of by Wassermann in a recent article.* 



2. The identity in a given serum of the bacteriolytic and the 

 hemolytic alexin. 



A normal serum, say from the guinea-pig, in presence of an anti- 

 cholera sensitizing substance attacks vibrios and causes their gran- 

 ular transformation. The same normal serum destroys red blood 

 corpuscles in presence of a hemolytic sensitizing substance. When 

 the normal serum is heated to 55 degrees it has no longer either 

 bacteriolytic or hemolytic effect even in the presence of appropriate 

 sensitizing substances. This fact is explained by saying that heat- 

 ing to 55 degrees destroys the alexin, which causes cytolysis.f The 

 question arises as to whether normal guinea-pig serum contains a 

 single alexin that is both hemolytic and bacteriolytic, or several 

 alexins, one or several of which can destroy bacteria and the other, 

 or several of which, preferably attack red blood corpuscles. This 

 question is open to experimental proof. 



W T hen normal cholera vibrios are mixed with normal guinea-pig 

 serum they are not destroyed, but are only slightly affected, since, 

 not being sensitized, the alexin cannot react with them4 If to such 

 a mixture sensitized corpuscles are added (that is to say, rabbit 

 corpuscles plus hemotoxin heated to 55 degrees) we find that they 

 are at once destroyed, which proves that the normal cholera vibrios 

 have neither transformed nor fixed the alexin necessary for destruc- 

 tion of corpuscles. 



We may repeat this experiment with a modification. We may 



* Wassermann, Deutsche medicinische Wochenschrift, 1900. 



f Heating to 55 degrees destroys the cytolytic property, not only of guinea-pig 

 serum, but also of sera from the rabbit, rat, goat, hen, etc. 



% We already mentioned some time ago (see p. 61, 1895) that normal serum 

 destroys few vibrios unless they be very attenuated. 



