THE COMPOUND H^MOLYSINS 241 



very simple substance, namely, mercuric chloride. 1 As 

 this process is rather perspicuous and indicates the mode 

 of action of lecithin, we will take it under consideration 

 for some moments. 



In weak doses mercuric chloride acts haemolytically ; in 

 greater concentration it agglutinates the erythrocytes and 

 the haemolysis is weak or insensible. At a certain con- 

 centration, therefore, the degree of haemolysis passes 

 through a maximum. The disappearance of the haemo- 

 lytic action at higher concentrations is regarded as due to 

 the hardening of the protoplasma and especially of the 

 membranes of the erythrocytes, whereby the passage of 

 haemoglobin through it is hindered. As Sachs has 

 shown, 2 it is possible to provoke the haemolysis of such 

 hardened erythrocytes by treating them with solutions of 

 potassium iodide or hyposulphite of sodium or of albumen, 

 which all take away a deal of the mercuric chloride from 

 the erythrocytes, which have been in contact with a solution 

 of this substance. 



The observed maximum, therefore, in this case depends 

 upon a double action of the mercuric chloride, one de- 

 structive, whereby the erythrocytes give away their haemo- 

 globin *-to the surrounding fluid, and one hardening, 

 whereby the permeability of the membranes of these 

 cells is checked. It is well possible that other similar 

 cases, in which maxima are observed, as for instance with 

 the botulismus-poison or with mixtures of saponin and 



1 Detre and Sellei: Berl. klin. Woe kens chrift, No. 30 (1904); Wiener 

 klin. Wochens chrift, Nos. 45 and 46 (1904); No. 30 (1905). Sachs: 



Wiener klin. Wochenschrift, No. 35 (1905). 



2 Sachs: Miinchner medicinische Wochenschrift, No. 5 (1902). 



