COXCERXIXG H.EMOLYSINS. 19 



hour and then centrifuged. The sediments thus obtained were 

 washed with salt solution and again centrifuged. If now to one 

 of these sediments physiological salt solution was added, and to 

 the other 1.5 cc. guinea-pig serum, complete solution resulted in the 

 latter, while the former remained undissolved. This proves that 

 the interbody was completely anchored by the blood-corpuscles. 

 The fluid obtained by centrifuging did not dissolve guinea-pig 

 blood, even when considerable guinea-pig serum was added. It 

 did not, therefore, contain any free interbody derived from the dog 

 serum first added. 



By these experiments we became convinced that ha?molysis in 

 general is due, not to a simple body, but to the combined action of 

 two distinct substances. At the present time we have no general 

 method to demonstrate this for each individual case, and the solution 

 of the problem therefore is now possible only under either of the 

 above-mentioned favorable conditions: (!) when the two hap- 

 tophore groups of the interbody differ greatly in their affinity; and 

 (2) when, by means of a combination whose discovery depends on 

 chance, an activating complement is found. Where these conditions 

 are not fulfilled, the solution of the problem, for the present at least, 

 is impossible. This, for example, is the case with ichthyotoxin, the 

 hsemolytlc constituent of eel serum. It is extremely easy to inactivate 

 this eel serum, slight warming for fifteen minutes to 54 C. sufficing, 

 but thus far we have been entirely unsuccessful in reactivating it, 

 because we have been unable to find the requisite complement. 



Considering their multiplicity, it is but natural that we are only 

 just getting a deeper insight into the nature of the substances in 

 normal blood serum. It is obvious also that a great many questions 

 whose solution is of importance present themselves, especially in 

 connection with the substances discussed by us. 



The first question to be considered is that of the multiplicity of 

 the haemolysins contained in a given normal serum. According to 

 our observations it is very probable that the ability of serum of one 

 species to dissolve the blood-cells of various other species is de- 

 pendent on the action, not of a single lysin, but of several lysins. 

 If, for example, dog serum dissolves the blood-cells of guinea-pigs 

 and of rabbits, it must be assumed that a multiplicity of interbodies 

 and of corresponding complements effects this action. Some of the 

 ways in which the solution of this problem can be approached are 

 as follows: 



