342 COLLECTED STUDIES IN IMMUNITY. 



Finally, in studying the complements of a serum it is often of 

 considerable importance to determine their plurality. The methods 

 leading to a differentiation of the separate complements have been 

 described in detail in a number of places, so that we can here con- 

 tent ourselves by referring to the studies of Ehrlich and Morgenroth 

 (pages 11-56, 110), of Ehrlich and Sachs (page 195), and of Marshall 

 and Morgenroth (page 222). 



VII. The Study of Antihaemolytic Actions. 



The subject of antihsemolytic functions, which has only recently 

 been carefully worked up, has attained considerable importance 

 for the comprehension of the mechanism of hsemolysins. Although 

 at the present time the study of the influences inhibiting haemolysis 

 is not at all complete, it is possible at least to indicate certain gen- 

 eral principles. 



We shall begin with the simple hsemotoxins, which are character- 

 ized by a cytophile haptophore group and a zymotoxic group. 

 (Analogous to these are the hsemagglutinins, also characterized by 

 a cytophile haptophore group and an agglutinating group.) If we 

 analyze the action of these hsemotoxins, we see that this can be inhib- 

 ited in two ways: 



(1) By means of an antibody which fits into the haptophore 

 group and -so deflects this from the receptor of the cell. 



(2) By means of substances which are capable of occupying 

 the receptor of the blood-cell and so block this for the entrance of 

 the hsemo toxin. 



So far as the first group is concerned, such antibodies are well 

 known for a large number of blood poisons. We need only call to 

 mind the antihsemolysins, such as anticrotin, antitetanolysin, anti- 

 staphylolysin, antibodies against the hsemolytic venoms of snakes, 

 spiders, and toads. Besides these there are the antiagglutinins, such 

 as antiricin, antiabrin, anticrotin. These substances can be produced 

 as antitoxins by means of immunization, but they also occur in 

 normal serum, as, for example, antitetanolysin in horse serum (Ehrlich), 

 antistaphylolysin in serum from goats, man, and horse (M. Neisser 

 and Wechsberg). 



The second method of inhibition is effected by substances which 

 occupy the receptors of the cells. Hence these must be substances 

 which possess the same haptophore group as the hsemotoxins them- 



