146 INFECTION AND RESISTANCE 



place, union with complement occurs, but only at temperatures above 

 C. (the speed and completeness of the union increasing as the 

 temperature approaches 40 C.), and the result of the union is lysis 

 or, in the case of bacteria not easily soluble, the bactericidal effect. 



Early in their researches, Ehrlich and Morgenroth were led to 

 speculate upon the possibility of the formation of lytic antibodies 

 within the animal against its own tissue cells. It would be of 

 the greatest importance to pathology, as they point out, if it could 

 be shown that an animal could produce hemolysins, for instance, 

 against its own blood cells. Thus, if an extensive internal hemor- 

 rhage occurred from trauma or other cause, in the course of which 

 considerable quantities of erythrocytes are subjected to disintegra- 

 tion and absorption, it is at least conceivable that specific "auto- 

 hemolysins" might appear which would lead to a chronic destruction 

 of the red cells, with consequent anemia. This form of reasoning, 

 as we shall see, has been extensively applied in the case of the cyto- 

 toxins for the explanation of a variety of pathological conditions. 

 Ehrlich and Morgenroth approached the question experimentally in 

 their further work on the hemolysins in goat blood. They found that 

 it was comparatively easy to produce hemolysins in one goat by 

 treatment with the erythrocytes of other goats, isohemolysins, as 

 they called them. 



Although, however, the blood serum of such an immunized goat 

 was strongly hemolytic, not only for the blood cells of the goats 

 whose blood had been injected, but also for the erythrocytes of cer- 

 tain other goats (though not, as we shall see, for goats in general), 

 it was never in any case active against this goat's own cells. More- 

 over, while the other sensitive erythrocytes could absorb the hemo- 

 lytic antibody out of the inactivated serum, 'the insensitive corpuscles 

 of the goat himself seemed to possess no affinity whatever for the 

 lysin of his own serum ; mixed with the serum they failed to absorb 

 out the hemolysin. This was in no sense, therefore, an autolysin. 



These experiments show a remarkable individual variation be- 

 tween the similar tissues of animals of the same species, since Ehr- 

 lich and Morgenroth were indeed able to show that the insensibility 

 of the goat's own corpuscles depended upon a complete absence of 

 receptors for the isolysin. For, to explain the lack of "autolytic" 

 action of such a serum, two possibilities could be assumed. One, as 

 above, that the corpuscles of the goat possessed no receptors by means 

 of which the isolysin could be "anchored" or, second, that, although 

 such receptors were present, they were already satisfied, or saturated 

 with the lysin in the blood stream. In the latter case it would be 

 hard to understand why hemolysis had not taken place. 



In order to completely disprove the latter possibility, Ehrlich 

 and Morgenroth did not allow the matter to rest upon conjecture, but 



