198 RALPH S. LILLIE. 



sides of various kinds (saponin, solanin, agaricin, quillain, etc.); 

 these increase the permeability of blood corpuscles, liberating 

 haemoglobin and eventually destroying the cell. Such substances 

 alter the plasma-membrane partly by their action on the lipoids 

 (lipoid-soluble alkaloids), partly by some specific action on the 

 proteins, as apparently in the case of foreign blood sera. (4) Pho- 

 todynamic substances (eosin, fluorescein, chlorophyll, 1 etc.) ; these 

 also appear to act in the light primarily on the plasma-membrane, 

 increasing its permeability. Tappeiner's observations 2 indicate 

 clearly that eosin solutions first effect the peripheral layers of the 

 cell. Paramsecia exposed to solutions of the dye in the dark, 

 washed free, and then exposed to the light are but little affected ; 

 blood corpuscles show a certain difference in behavior and allow 

 some entrance of the dye in the dark, but haemolysis is much 

 more rapid if the corpuscles are illuminated while in the solution, 

 than if, after equally prolonged treatment in the dark, they are 

 transferred to an eosin-free medium and then illuminated : i. e., 

 the effect is largely if not exclusively dependent on a surface 

 action. Harzbecker and Jodlbauer 3 find the same general result. 

 Microscopical observation also indicates that the initial stage of 

 the destructive action consists in a disturbance of the osmotic 

 equilibrium between corpuscle and medium, such as would result 

 if the semi-permeability of the plasma-membrane were abolished. 

 The corpuscles first swell, indicating entrance of water ; this occurs 

 before any perceptible entrance of the dye. P. v. Baumgarten 4 

 finds the same initial change in the action of haemolytic substances, 

 and has referred haemolysis primarily to a loss of osmotic equi- 

 librium consequent on alteration of the surface layer. This view 

 is also upheld by Hamburger. 5 The increase in permeability, in 

 addition to destroying the osmotic equilibrium, will naturally 

 further the entrance of the toxic substance and the action will 

 then affect the entire cell. In general toxic action must be re- 

 garded as depending in many cases primarily on an alteration, 

 particularly an increase, in the normal permeability of the cells. 



1 Hausmann, Biochemische Zeilschrift, 1909, XVI., p. 294. 



2 Tappeiner, Biochemische Zeitschrift, 1908, XII., p. 290; ibid., XIII., p. I. 



3 Harzbecker u. Jodlbauer, Biochemische Zeitschrift, 1908, XII., p. 306. 



4 P. v. Baumgarten, ibid., 1908, XI., p. 21. 



5 Hamburger, loc. cit., vol. 3, p. 360. 



