142 INFECTION AND RESISTANCE 



process, like that of bacteriolysis, was specific in that the hemolytic 

 power was lost if the serum was heated to from 50 to 60 C., but 

 could be restored undiminished by the addition of a little fresh nor- 

 mal serum, in itself possessing no hemolytic properties for the given 

 species of cell. The specificity of the phenomenon again was seen 

 to reside entirely in the heat-stable factor, the heat-sensitive or 

 "alexin" factor being non-specific, and not increased during the 

 process of immunization. 



Observations related to those of Bordet concerning hemolysis 

 were made independently, in the same year, by Belfanti and Car- 

 bone, who had observed that the serum of animals treated with blood 

 cells of another species became toxic for this species, and extensive 

 confirmation of the phenomenon of hemolysis was obtained, in the 

 year following, by the work of von Dungern, and by that of Land- 

 steiner. 



After Bordet had thus established the important fact that hemol- 

 ysis was in every way analogous to bacteriolysis in that, like bac- 

 teriolytic sera, hemolytic sera could be inactivated by heat, but re- 

 activated by the addition of small quantities of fresh normal serum, 

 Ehrlich and Morgenroth 18 undertook an elaborate study of the 

 mechanism of hemolytic phenomena, hoping thereby to elucidate the 

 mechanism of lysis in general. For it is obvious that hemolysis 

 lends itself far more easily to experimentation than does bacteriol- 

 ysis, and, as we shall see, experiments on hemolysis can be made 

 with a considerable degree of accuracy. Ehrlich and Morgenroth 

 approached the investigation of the hemolysins from the point of 

 view of the side-chain theory, formulated by Ehrlich in connection 

 with his work on the toxins. According to this theory, it will be 

 remembered, the hemolytic substances in the sera of animals treated 

 with blood corpuscles represent the receptors or side chains of tissue 

 cells. These receptors were originally integral chemical elements of 

 the body cells, by means of which the cell became united to the 

 injected erythrocyte (or bacterial) protein. Since union with the 

 foreign substance blocked these receptors or side chains, thereby 

 rendering them useless, they had been regenerated and, under the 

 influence of immunization, regenerated in excess, cast off by the cell, 

 and were now free in the blood stream as hemolysins (or bacteriol- 

 ysins). 



If this conception of the process was the correct one, Ehrlich 

 and Morgenroth argued, the hemolytic substances of any immune 

 hemolytic serum should possess specific chemical affinity, "hapto- 

 phore groups," as they expressed it, for the blood cells which had 

 been used in the immunization. 



In order to show this, they inactivated at 56 C., by the method 



of Bordet, a goat serum which was hemolytic for beef blood, left it 



18 Ehrlich and Morgenroth. Berl klin. Woch., Nos. 1, 21, and 22, 1900. 



