BACTERIOLYSIS AND ALLIED PHENOMENA 147 



the red corpuscles, but the molecules of the complement still 

 remain free, and do not attach themselves either directly or in- 

 directly to the corpuscles. Nevertheless, there is a change in the 

 combining affinities of the complementophile haptophore. 1 This 

 is shown by the fact that if the mixture be raised to the body- 

 heat, the molecules of complement attach themselves to these 

 haptophores, exert a digestive or haemolytic action through the 

 amboceptor on the red corpuscles, and haemolysis occurs. Hence, 

 on Ehrlich's theory, the complement does not attack the cell or 

 corpuscle direct (as Bordet holds, and as is implied in the term 

 substance sensibilatrice for amboceptor), but it unites itself to 

 one part of the molecule of amboceptor after another part of the 

 latter has combined with the corpuscle. We will defer the 

 discussion of these theories for the present. 



For the sake of simplicity, we have assumed that complement 

 will not unite with amboceptor until the latter has combined with 

 its antigen. Ehrlich, however, assumes (on no very clear evidence) 

 that the two substances may enter into a loose and easily dis- 

 sociated chemical combination. This is hastened by heat and 

 retarded by cold. The union between corpuscle and amboceptor 

 is a firm one, which takes place at low temperatures, and which 

 does not tend to dissociate, and after the combination amboceptor 

 has a stronger affinity for complement, though even then a firm 

 union only takes place at 30 C. or over. 



Ehrlich explains the method of formation of amboceptor on the 

 side-chain theory in this wise : He points out that for the 

 absorption of substances of small molecule by the cell protoplasm 

 the simple receptors, which, when cast off, constitute antitoxin, 

 may suffice ; but he says that when a giant proteid molecule (e.g., 

 of albumin) is anchored, it requires the action of a digestive 

 ferment before it can be brought into a condition to be of use 

 in the nourishment of the living cell. Hence it must be first 

 broken down by means of a proteolytic enzyme, and it is of this 

 nature that he imagines the complement to be. He holds, there- 

 fore, that the receptors or side-chains which are adapted to seize 

 molecules of coagulable proteid possess two haptophore groups, 

 the one to seize the nutrient material, and the other to seize a 

 molecule of digestive enzyme from the surrounding blood or 

 lymph. When the formation of such receptors is stimulated to 



1 Ehrlich does not make a definite statement as to this increase of affinity, 

 but it seems a necessary deduction from the facts as he interprets them. 



IO 2 



