92 COLLECTED STUDIES IN IMMUNITY. 



constitution in one respect, i.e. in being firmly bound to the proto- 

 plasm, so that a thrusting-off, which is essential for the formation 

 of antibodies, does not occur even with an increased regeneration 

 (sessile receptors). This leads to the conception that the regenera- 

 tion of the receptors may take two courses: (a) a thrusting-off 

 of the receptors ensues, and with this a formation of antibody; 

 (6) in the case of sessile receptors, a hypertrophic process sets in 

 comparable perhaps to a simple muscle hypertrophy, according to 

 Weigert's conception. Second, it is conceivable, as Morgenroth l 

 has shown in the immunization against rennin, that normal pre- 

 formed regulating contrivances come into action, for, in the case of 

 enzymes (in contrast to toxins) we are dealing with substances nor- 

 mally produced by the organism itself. Hence it is possible that the 

 formation of an antienzyme is followed by the production of the 

 enzyme itself, in consequence of an internal regulating contrivance. 



In any event these observations will show how the factors just 

 discussed can make it possible, when cells possessing numerous 

 different receptors are injected, that only a small number of the anti- 

 bodies theoretically possible is actually produced. It is therefore 

 very likely that the immunization of one animal species with a certain 

 kind of cell or bacterium results in the production of only part of the 

 possible antibodies. When, however, the same kind of cell or bac- 

 terium is injected into a second animal species, it is highly probable 

 that in this species the haptophore groups of the cells will find a 

 receptor apparatus which in part at least is different from that of 

 the first species The prere quisite for such a difference is the obvious 

 assumption that the receptor apparatus of one species is not identical 

 with the receptor apparatus of a second not very closely related 

 species. For example, it is possible that a certain haptophore group 

 a of the typhoid bacillus finds fitting receptors in the organism of the 

 rabbit, but not in that of the dog, whereas another group, b, finds 

 just the reverse conditions. If these presumptions are correct an 

 important principle for the practical production of curative sera will 

 follow, namely, that in any single case one would immunize a number 

 of different animal species, select the sera containing different immune 

 bodies, and by mixing these, produce a curative serum containing differ- 

 ent types of receptors in as complete a form as possible. 



Owing to the importance of this subject we have first under- 



1 Centralblatt fur Bacteriologie, Vol. 26, 1899. 



