STUDIES ON ILEMOLYSINS. 83 



exogenous injuries. We believe that the study of these regulating 

 contrivances is of the greatest importance and according to our 

 present investigations either the disappearance of receptors or the 

 presence of autoantitoxins is foremost among these contrivances. 

 It will therefore be necessary to subject all the factors which are of 

 importance in this respect to a thorough analysis. 1 



We shall now mention a few observations relating to the com- 

 plements which seem to point to a regulatory contrivance as yet 

 undescribecl. 



Normal rabbit serum possesses a number of properties which 

 are to be ascribed to the presence of complements. First to 

 be mentioned is the property by means of which freshly derived 

 rabbit serum is able to dissolve guinea-pig blood-cells. This is due 

 to the combined action of a complement and an immune body which 

 is present in the serum in comparatively small amounts. Further- 

 more, rabbit serum is regularly able to activate an immune body 

 derived by treating rabbits with ox blood. 



Now we noticed that rabbits which a week previously had been 

 treated with goat serum (whether active or inactive is immaterial) 

 had completely or almost completely lost these properties, and that 

 these changes persisted for weeks after the injection. Hence it fol- 

 lows that owing to the injection of goat serum, complement nor- 

 mally present had been made to disappear. It was therefore essen- 

 tial that the cause of this remarkable phenomenon be determined. 

 We could next show that frequently the serum of these rabbits in 

 its native state, though more surely after heating to 56 C., is able 

 to prevent the above-described complementary action of normal 

 rabbit serum. Hence in the above case normal complement has 

 evidently disappeared from the rabbit treated as described, and 

 has been replaced by an anticomplcment which we shall have to 

 term an autoanticomplement. 2 



1 Metalnikoff' s interesting observation is only apparently a contradiction 

 of these regulating phenomena. He found that a typical autospermotoxm is 

 developed in the blood of guinea-pigs which have been treated with guinea-pig 

 spermatozoa, and that this is able in vitro to kill the spermatozoa of the animal 

 itself. But such an injurious action on the spermatozoa does not take place, 

 even in the slightest degree, in the living animal, because, as Metalnikoff's 

 researches show, only the immune body combines with the spermatozoa, not 

 the complement. In this case, therefore, an autotoxin within our meaning, 

 one that destroys the cells of its own body, does not exist. 



2 According to the investigations of Dr. M. Neisser and Dr. Wechsberg still 



