222 LECTURES ON IMMUNITY 



the presence of haemolysin in the mixture of immune-body 

 and alexin. 



Overton has drawn attention to the fact that the alkaloids 

 are much more toxic to cells of animal or vegetable origin 

 than are their salts. This depends upon the circumstance 

 that the cell membranes are permeable to the alkaloids 

 themselves, but not so to their salts, or, more strictly speak- 

 ing, to their ions. The salts are poisonous at all only be- 

 cause they are to some extent hydrolysed in their watery 

 solutions; and therefore the salts of the weak acids are 

 more poisonous than those of the strong acids. Under 

 these circumstances an excess of acid diminishes the toxic- 

 ity of these salts, even to the point of complete suppres- 

 sion of toxic action. On the other hand, the presence of 

 substances with alkaline reaction sets the alkaloid free, and 

 thus increases the toxicity of the solution of the salt of an 

 alkaloid. (Cf . Hoeber, Physikalische Chemie der Zelle und 

 Gewebe, 2d ed., 1906, p. 165.) 



In some cases, which seem to be rather rare, the absorp- 

 tion of the immune-body by the erythrocytes is by far not 

 so evident as in the ordinary case represented by the 

 figures above (p. 1 50). Ehrlich and Sachs * describe some 

 experiments on the action of a mixture of inactivated ox- 

 serum and normal horse-serum on guinea-pigs' erythro- 

 cytes. These are at 37 C. laked by the said mixture 

 within one hour. But if the erythrocytes are suspended 

 for one hour at 37 C. in the ox-serum, and then after 

 centrifugation mixed with the horse-serum, no such re- 

 sult is observed. 



Ehrlich explains this observation as due to the circum- 



1 Ehrlich and Sachs: Berl. klin t Wochenschrifa No, 31 (1902). 



