STUDIES OX H.EMOLYSINS. 61 



interbody to be completely activated when the complement of guinea- 

 pig serum was used, contained only one-sixth the amount of interbody 

 which was completely activated when horse serum was used as 

 complement. From this, however, it follows that all the interbody 

 present hi dog-serum and possessing specific relations to the guinea- 

 pig blood-cells is not of the same uniform nature. In our case one- 

 sixth of the interbody acting on guinea-pig blood can be reactivated 

 by horse serum, while fully five-sixths can be reactivated by the 

 complement of guinea-pig serum. Therefore the goat serum con- 

 tarns two different interbodies for the same species of blood-cells, and 

 these can be positively separated by means of the difference in activa- 

 tion. 



In our second communication, by showing the existence of a 

 thermostabile and a thermolabile complement in the goat serum, 

 we also proved that the complements of a given serum need not 

 be of uniform nature. At that time we showed that the sera of 

 two bucks treated with sheep blood-cells, as well as the sera of a 

 number of normal goats, contained a complement which, hi con- 

 trast to the other complements of the same sera (for rabbit blood 

 and guinea-pig blood), was not destroyed by heating to 56 C. 

 Buchner finds it so hard to emancipate himself from his views that he 

 seeks to explain our observations by assuming we made a gross error 

 in the experiment. He supposes that the sheep serum still present 

 hi the 5% mixture of sheep blood-cells, and which we disregarded, 

 reactivated the inactive serum and led us to mistake it for a resistant 

 complement. We were well aware of this source of error and had 

 therefore, even hi the first communication, stated that the slight 

 amounts of sheep serum present in the blood mixture caused no dis- 

 turbances whatever. How, by the way, could it be explained that 

 these disturbances occurred only in the serum of certain animals 

 although the method of procedure was the same? Or, that digestion 

 of the serum with HC1, which does not injure the immune body, pre- 

 vented all solution whatever? 



After what has been said, we shall have to assume that in gen- 

 eral every serum which acts hcemolytically on various species of blood 

 possesses a corresponding multiplicity of interbodies, to which again 

 different complements may fit. Against the Unitarian views of 

 Buchner and of Bordet we must uphold the view that the experi- 

 mental results positively show a multiplicity of complements in 

 normal serum. This multiplicity of the haemolytic substances will 



