PRODUCTION OF H^MOLYTIC AMBOCEPTORS. 249 



faet that free receptors leave the serum to reappear in the urine seems 

 to make it probable that they have no significance for the organism 

 itself. On the contrary, one may suspect that these are products 

 of regressive metabolism which are eliminated from the body as 

 useless. The explanation that the free receptors originate from the 

 breaking down of red blood-cells or other cells is entirely sufficient. 

 It may be, however, that there is a physiological thrusting-off of 

 the same which bears some relation to their nutritive function. In 

 view of the elimination through the urine, it seems improbable that 

 this constitutes a regular function as anti-immune body against the 

 action of a possible autolysin. That certainly would be an unsuita- 

 ble process. In fact the free receptors evidently do not generally 

 possess the character of antiautolysins, as Besredka 1 believes, for 

 by injecting a rabbit with ox serum it was impossible to obtain any 

 haemolytic amboceptors. This corresponds to the negative results 

 obtained by London 2 on injecting guinea-pigs with rabbit serum. 



One thing is clearly shown by the presence of dissolved substances 

 capable of producing amboceptors, namely, that without the idea 

 of "receptors" a universally applicable conception of the origin and 

 mode of action of the cy to toxins is impossible, as is also a clear con- 

 ception of the nature of "specificity." 



Subsequent Note. In a recently published study (Munch, med. Wochen- 

 schr. 1902, No. 32) P. Th. Miiller reports on the production of haemolytic 

 amboceptors by treating pigeons with guinea-pig serum, and he accepts the 

 views here developed. 



1 Besredka, Annal. de 1'Institut Pasteur, Oct. 1901. 



2 London, Arch, des Sciences biologiques, St. Petersburg. 



