STUDIES ON H.EMOLYSINS. 73 



interesting experiments, by which he believed to refute our theory 

 of the mechanism of haemolysis, has been discussed by us in our 

 fourth communication l and controverted by means of extended quan- 

 titative experiments. 



It is necessary, however, once more to thoroughly discuss the 

 binding of immune body to the erythrocyte, for on this point the 

 views seem not at all clear, because the purely chemical conception is 

 denied by some authors or is regarded as unimportant. 



I. The Manner in which the Immune Body Combines with the 



Erythrocytes. 



In our first communication we had already shown that the ery- 

 throcytes as such behave quite differently toward the two components 

 which effect haemolysis. The blood-cells abstract the immune body 

 from its medium with great avidity, whereas they do not take up the 

 slightest trace of complement. When loaded with immune body, 

 however, they are able to anchor the complement also. From this 

 we have concluded primarily that the immune body possesses two 

 combining groups of different affinity, of which the one combines with 

 a corresponding group, the receptor of the blood-cell; the other com- 

 bines with the complement. But according to our view these combi- 

 nations are pure chemical phenomena proceeding between immune 

 body and blood-cells and between immune body and complement. 



The function of the immune body can be elucidated by means of 

 a chemical example, that for instance afforded by the behavior of 

 diazobenzaldehyd. Through its diazo group this substance can 

 unite with a series of bodies, especially with amines, phenols, keto- 

 methylen groups, whilst the aldehyd group on its part can effect a 

 series of syntheses e.g. with hydrazins, hydrocyanic acid, etc. It 

 thus becomes easy by means of diazobenzaldehyd to effect a com- 

 bination between substances which by themselves do not combine, 

 as phenol and hydrocyanic acid. Such a combination includes both 

 substances. In order to make the comparison still closer let us imagine 

 that certain constituents of the living cell, say by means of an aro- 

 matic group, are able to unite with the diazo combination. In 

 this case it follows that by means of the aldehyd group of the diazo- 

 benzaldehyd a second highly toxic nucleus e.g. that of hydrocyanic 

 acid can be joined to the combination in such fashion that the proto- 

 plasmal molecule is now subjected to the action of the strongly 



1 See page 56. 



