POWER OF NORMAL SERUM TO DEFLECT COMPLEMENT. 611 



being hidden by the normal amboceptors which are removed by 

 the digestion with blood-cells or bacteria. 



Gay believes otherwise. He has repeated my experiments, 

 especially those dealing with haemolysis, and concludes that my 

 explanation is "certainly incorrect." Gay believes that the cause 

 of the phenomenon described is to be sought in a binding of com- 

 plement by precipitates. According to him the* precipitin is in the 

 sheep-blood immune serum; the precipitable substance is in the 

 rabbit serum digested with sheep b ood and comes from traces of 

 serum remaining on the sheep blood after insufficient washing. 

 This explanation, at first sight, seems most reasonable. We know 

 from the researches of Gengou l that the combination resulting 

 from the union of serum albumin and a corresponding antiserum 

 has the power to bind complement. Through the recent investiga- 

 tions of Moreschi 2 and of Gay 3 a great deal of interest has been 

 aroused in this property, and M. Neisser and I 4 have reported on 

 experimental studies in which we sought to utilize the complement- 

 binding power of albuminous bodies laden with antiserum in a 

 forensic blood test. For the question here at issue it matters not 

 whether the precipitate as such absorbs the complement, or whether, 

 as we believe, the albuminous bodies are sensitized by specific 

 amboceptors in Gengou's sense, so that they then bind the com- 

 plement just as do sensitized cells. The main point is that accord- 

 ing to Gay's view the inhibition of haemolysis must be due to the 

 interaction of sheep serum and the immune serum acting on sheep 

 blood. 



The experiments made by Gay apparently corroborate his assump- 

 tion. Thus when the sheep-blood corpuscles used for treating the 

 rabbit serum were washed five successive times with physiological 

 salt solution, he found that the centrifuged rabbit serum no longer 

 produced inhibition, whereas when the serum was treated with 

 sheep blood washed but once, it produced the inhibition which 

 I had described. The difference which I observed in the behavior 

 of normal and immune amboceptors of rabbit serum, so far as 

 the inhibiting action of rabbit serum treated with sheep blood 

 is ^concerned, Gay believes, is only an apparent one. Normal 



1 Gengou, Annales Pasteur, Tome XVI, 1902. 



2 Moreschi, Berliner klin. Wochenschrift, No. 37, 1905. 



3 Gay, Centralblatt Bacteriologie, Orig. XXXIX, 1905. 



4 Neisser, M., and Sachs, Berliner klin. Wochenschrift, No. 44, 1905. 



