CYTOLYSINS 123 



washed three times and resuspended in salt solution to a volume of i.o 

 c.c. To this was added i .o c.c. untreated corpuscle suspension, the tube 

 shaken and placed at 37 C. for one hour. At the end of this time 

 four units of complement were added, the tube incubated again for 

 one hour and complete hemolysis was found. Thus it was found that 

 the original cells yielded at least one unit of amboceptor for the new 

 cells. Although in the report cited on page 120, twelve units gave one 

 free unit, Muir states that usually one unit of amboceptor can be 

 obtained from corpuscles containing six units. In this experiment the 

 dissociation was at 37 C., but dissociation takes place at room tem- 

 perature, although more slowly, and at o C. it is practically nil. By 

 working with sensitized cells and with supernatant fluids, it is possible 

 to titrate the latter so as to determine the exact quantities of ambo- 

 ceptor dissociated. Kosakai, in working with so-called pure hemolysins, 

 has recently shown that the antigen and amboceptor union is reversible to 

 a greater extent than has previously been supposed. He main- 

 tains that the reversibility under these circumstances is almost or 

 quite complete. 



Specificity of Amboceptors. Group Reactions. The hemolytic 

 amboceptors are highly specific, but show, as do other immune bodies, 

 group reactions. Ehrlich and Morgenroth showed that immune sera 

 prepared against ox blood are hemolytic also for goat and sheep blood 

 and that a hemolysin prepared against goat blood also dissolves ox 

 blood. Marshall showed that an antihuman hemolysin acts on monkey 

 blood and vice versa. In any case the hemolysin is most active in the 

 presence of the antigenic corpuscles. Treatment of a hemolytic im- 

 mune serum with heterologous corpuscles removes more of the specific 

 immune body than is the case in other group reactions. For example, 

 Muir developed an anti-ox-blood serum which, in a dose of 0.0005 c.c. 

 dissolved i.o c.c. 5 per cent, suspension ox corpuscles and, in a dose 

 of 0.0012 c.c. dissolved a similar suspension of sheep corpuscles. Ab- 

 sorption by sheep corpuscles in excess reduced the titer against ox cor- 

 puscles so that the serum dissolved the latter in doses of 0.0012 c.c. ; 

 in other words, the titer of the serum was reduced to about half its 

 original strength, Ehrlich and Morgenroth showed that if the quantity 

 of sheep corpuscles is carefully adjusted so as exactly to equal the 

 hemolytic power for such corpuscles, the fraction of amboceptor lytic 

 for sheep corpuscles may be absorbed without reducing the titer against 

 ox cells. If, however, the amboceptor for ox blood is removed by 

 absorption with ox corpuscles the hemolytic power for sheep corpuscles 

 is entirely destroyed. Thus it is seen that there is close similarity with 

 the group reactions of agglutinins and other immune bodies. Ehrlich 

 and Morgenroth explain the phenomenon by assuming that each ambo- 

 ceptor contains numerous " partial amboceptors " formed in the im- 

 mune animals in response to relatively undifferentiated receptors of the 

 antigenic cells. In other words, ox-blood corpuscles are supposed to 

 contain a certain number of receptors specific to those cells, and in 

 addition other receptors that are closely* similar to or identical with 



