I9I2] 'Alfred P. Lothrop 167 



The restoration of complement activity by putting together the albu- 

 min and globulin fractions does not prove, however, that each 

 fraction contained a part of the complement, for the albumin 

 fraction can be reactivated in the absence of the globulin fraction. 



Complement-splitting as brought about by hydrochloric acid, 

 carbon dioxid, and dialysis, is really an inactivation of the whole 

 complement by certain acids or alkalis, either added in the free 

 State to the serum, or liberated as a result of the dissociation of 

 certain electrolytes. 



That the whole complement, and not a part only, is present in 

 the albumin fraction of the serum can be demonstrated by the re- 

 moval of the inhibitory action of the acid or alkali. This can be 

 effected by the addition, not only of alkali or acid, but also of any 

 amphoteric substance. When hydrochloric acid, carbon dioxid, or 

 dialysis are employed to produce the phenomenon known as com- 

 plement Splitting, the complement is merely inactivated, not split. 



B. Thus far, most investigators have made but little distinction 

 between the Splitting phenomenon obtained by chemical interference 

 and that which takes place in the biological phenomenon known as 

 complement fixation. In this study we have shown that these two 

 sets of phenomena exhibit certain fundamental differences and that 

 the so-called complement Splitting by physical conditions leading to 

 chemical interaction, or directly by chemical means, is not a real 

 Splitting of the complement, but an inactivation of the active prin- 

 ciple of complement through an alteration in the reaction of the 

 medium caused by an excess of either anions or cations. The modi- 

 fication of the reaction of the medium may cause a more or less 

 definite combination of the complement with the free ions, but the 

 latter can readily be removed by an appropriate number of opposite 

 ions, and render the complement active once more. The fluids that 

 have hitherto been regarded as containing the end-piece of com- 

 plement, contain, as a matter of fact, the whole complement tem- 

 porarily deprived of its activity by certain ions derived either from 

 the Salt constituents of the serum itself under a modified physical 

 condition (dialysis against water or dilution with water) or intro- 

 duced in the form of dissociable electrolytes. 



On the other hand, the Splitting of complement in the fixation 



