H&MOLYSINS. 33 



diately dissolved. Now, to the clear centrifuged 

 fluid, which as we have seen would not dissolve 

 rabbit red cells, they added guinea-pig red cells 

 and again some normal horse serum to reactivate 

 the mixture. The guinea-pig red cells all dis- 

 solved. This proved conclusively that in the nor- 

 mal goat serum there had existed two specific inter- 

 bodies. One, for rabbit red cells, had been tied 

 by these cells and carried down with them in cen- 

 trifuging; the other, specific for guinea-pig red 

 cells, had remained behind. 



Multiplicity of the Active Substances. These in- 

 vestigators were able to prove still more in regard 

 to the multiplicity of the substances in normal 

 serum which are concerned in haemolysis. They 

 showed that beside the two inter-bodies just men- 

 tioned there existed in goat serum two specific 

 complements, one for each inter-body, arid they 

 were able by means of Pukall filters to separate 

 these two. In this filtration the complement fit- 

 ting the inter-body for rabbit blood remained 

 behind for the greater part, while that fitting 

 the inter -body for guinea-pig blood mostly passed 

 through. 



Whereas then, according to Buchner, only one 

 substance, the alexin, is concerned in the haemo- 

 lytic action of this normal goat serum, these experi- 

 ments of Ehrlich and Morgenroth show us four 

 substances, viz., two inter-bodies and two comple- 

 ments, This at once makes clear the opposing 



