METHODS OF STUDYING HJEMOLYSINS. 339 



the amboceptors for sheep blood or ox blood by means of goat 

 serum. 



But it is often possible to complement an amboceptor with a 

 serum which in itself dissolves the blood-cells, but which, in the 

 amounts in which it is able to effect completion, has little or no 

 haemolytic action. It is obvious that in such cases the solvent power 

 of the serum by itself must be accurately determined by means of 

 controls. While this method is often successful, the relation in these 

 sera between the normal amboceptor and the complement is fre- 

 quently so unfavorable that it is impossible to complement the 

 foreign amboceptor. In such cases one can get rid of the normal 

 amboceptor by anchoring it to blood-cells at low temperatures, as 

 Flexner and Noguchi l have recently done in order to obtain com- 

 plements for the hsemoh'tic amboceptors of snake venoms. Or one 

 can attempt artificially to increase the amount of complement con- 

 tained in complementing serum, after the method of P. Miiller. 2 

 This author succeeded in effecting a considerable increase in the 

 complements of chicken serum, by injecting the animals with solu- 

 tions of peptone. 



So far as the choice of the complementing sera is concerned it is 

 obvious that, in amboceptors produced by immunization, whenever 

 possible the preference will be given to those sera which are derived 

 from the same species which yielded the amboceptor. For the 

 remaining cases the principle may be formulated that that serum 

 is most useful which is derived from a species closely related to that 

 furnishing the amboceptor, because often in distantly related species 

 partial amboceptors present only in very slight amounts are com- 

 plemented. 3 



Another point of considerable importance in the completion of 

 amboceptors is the manner in which the sera are inactivated. As 

 a rule inactivation is effected by heating the serurn for half an hour 

 in a water-bath. According to recent investigations special atten- 

 tion must be paid to the degree and duration of this action. 4 



1 Flexner and Xoguchi, Journal of Exp. Medicine, Vol. VI, 1902. 



2 Miiller, Centralblatt f. Bacteriologie, Orig. Vol. 29, 1901. 



3 Ehrlich and Morgenroth, see pages 110 et seq. 



4 In order accurately to observe the temperature constantly maintained 

 it is well to use thermometers with particularly wide divisions on the scale 

 (1 C. = l cm.). These thermometers need only embrace a moderate range of 

 degrees (about 40-80 or 45-85), They can be obtained from A. Haak 

 in Jena.. 



