96 IMMUNE SERA 



the isolysin, and proceeding in the same series of 

 experiments which we have already studied under 

 haemolysis, Ehrlich and Morgenroth showed that 

 the isolysins, like the haemolysins, consist of an 

 immune body and a complement of the normal 

 serum. The experiments undertaken by these 

 authors were made on thirteen goats, and the sur- 

 prising fact developed that the thirteen resulting 

 isolysins were all different. For example, the iso- 

 haemolytic serum of one goat dissolved the red cells 

 of goats A and B; that of a second goat those of 

 C and D ; of a third those of A and D, but not of (7, 

 and so on. If now they produced antiisolysins by 

 injecting animals with these isolysins, they found 

 that these antiisolysins were specific; i.e., the anti- 

 isolysin of A would inhibit the action only of iso- 

 lysin of A, but not of C, etc. These results are of 

 the highest clinical interest, for they show a differ- 

 ence in similar cells of the same species, something 

 that had never before been suspected. In the 

 above, the blood cells of species A must have a dif- 

 ferent biological constitution than those of species 

 C, etc. 



The fact that after injections of large amounts of 

 cells of the same species isolysins develop, but that 

 autolysins are almost never formed, caused Ehr- 

 lich and Morgenroth to assume that the body pos- 

 sesses distinct regulating functions which naturally 

 prevent the formation of the highly destructive 



