BACTERIOLYSIS AND ALLIED PHENOMENA 151 



There are, therefore, three possibilities : no formation of haemo- 

 lysin, the formation of an isolysin, and the formation of an anti- 

 autolysin. In other words, if autolysins were ever developed they 

 would be followed immediately by the production of their specific 

 antibody. 



But Ehrlich assumes and our previous account of the iso- 

 agglutinins leads us to be ready to accept his assumption 

 unhesitatingly that each corpuscle in every animal has numerous 

 side-chains, a, ft, y, etc. If such a corpuscle is injected into 

 an animal of the same species, a may lead to no result, finding no 

 receptors ; /? may lead to the production of an isolysin, and y to 

 that of an anti-autolysin. The existence of the latter substance 

 could not, of course, be proved, since it was never possible to 

 prepare autolysin. 



Hence what Ehrlich calls the " pluralistic conception of the 

 cellular immunity reaction." There are, he says, in each bac- 

 terial cell numerous side-chains, to each of which an antibody 

 is theoretically possible, and an ideal curative serum would 

 contain all these antibodies. But in some cases, perhaps in most, 

 only a few are found, and others cannot be developed ; for 

 instance, in some animals it is impossible to produce anti-enzymes 

 by the injection of enzymes. He explains this in two ways. 

 The specific receptors may be of peculiar constitution, so that they 

 cannot be cast off from the cell in the process of immunization : 

 these he calls sessile receptors. Secondly, it is conceivable that 

 the side-chains in question are normally produced by the animal 

 cells, and that no antibody is produced to them, or, at any rate, that 

 none accumulates. 



But when either or both of the conditions arise, we may be able 

 to get the antibodies from a second animal which we are unable 

 to do from the first. Thus, if we imagine that the typhoid bacillus 

 has twenty different sorts of side-chains, we may be able to get 

 antibodies to some of them from the dog, to others from the rabbit, 

 etc. Hence he suggests as an important principle in the forma- 

 tion of curative sera to use many animal species, mixing the sera 

 of those which produce the antibodies required for use. (This, it 

 must be pointed out, is not what is meant by a polyvalent serum, 

 which is a serum formed by the injection of many strains of the 

 same organism.) 



Leaving this subject for the present, we will pass on to Ehrlich's 

 researches into the nature of complements. Buchner, in his 



