STUDIES ON H.EMOLYSIXS. 93 



taken the experimental study of the preliminary question whether 

 mmune sera derived by treating two different animal species with the 

 same cells are identical so far as their antibodies are concerned, 

 or whether they are partly or wholly different. Of these antibodies 

 the most important are the bacteriolytic and hsemolytic immune 

 bodies. According to our conception, as is well known, these 

 possess two haptophore groups, one, the complementophile group 1 

 and the other (which anchors itself to the receptors of the cells 

 causing the immunity) which we can briefly designate the cytophile 

 group. According to what has been said above it is this second 

 group which possesses special significance in the question under 

 discussion, and we may therefore formulate our problem as follows: 

 To determine whether, in the immunization of different animal species 

 with cells of one kind, amboceptors (immune bodies) possessing different 

 cytophile groups arise. 



The experimental study of this question can be pursued in the main 

 in two different ways: 1, by means of the absorption test which, 

 although it is very difficult, is applicable to bacteriolysins as well 

 as to haBmolysins; 2, by neutralization with antiamboceptors (anti- 

 immune bodies). 



The latter way, the more elegant of the two, is, however, 

 presumably applicable only to those immune bodies which are 

 directed against cells of the organism. A hosmolytic or cytotoxic 

 immune body, as is to be expected, always finds points of attack 

 in the organism of the corresponding animal species, for this is 

 the first prerequisite for the possibility of an anti-immune body. 

 As a matter of fact also, such anti-immune bodies have already 

 been observed. On the other hand, the immune bodies of bacteri- 

 cidal sera, since their natural counter groups are found in the 

 bacterial cells, will in all probability not find these groups in the 

 cells of the higher animals. Hence it seems improbable, unless by 

 chance they occur in an isolated case, that anti-immune bodies 

 directed against the bactericidal immune bodies will be produced. 



II. Concerning the Variety of the Cytophile Groups of Homologous 



Immune Bodies. 



We selected immunization with ox blood-cells as being especially 

 adapted for these experiments. Such immunization had already 

 been carried out by von Dungern on rabbits. The production of 

 immune bodies in high concentration succeeds particularly well in 



