DIFFUSION OF TWO AGENTS 145 



to how the chemical exciters of reproduction act in 

 the causation of mitosis. 



Another point is learnt, however, by experimenta- 

 tion with this combination of. stain and atropine, for 

 here we have two chemical agents, an anilin dye 

 and an alkaloid, both diffusing into the cells side by 

 side and each producing its effect on the cell-proto- 

 plasm. One excites the cell, the other kills it, and 

 each carries out its function in direct proportion to 

 its own concentration; for if the content of the stain 

 in the jelly is reduced, the cells become less stained, 

 and death is delayed; but if the alkaloid alone is 

 reduced, the staining is as usual, but there is less 

 excitation. At the same time, it must be remembered 

 that the alkaloid is a salt, and, like other salts, as it 

 diffuses itself into the cell, it delays the diffusion of 

 the stain. 



The diffusion of a combination of substances into a 

 cell, therefore, is not a simple matter, for it represents 

 an equation of variables, although those variables, if 

 applied in the same manner, always have the same 

 effect with mathematical precision. 



The excitation of amoeboid movements in white 

 corpuscles is due entirely to the atropine. Using a 

 jelly-film which is alkaline, 1 and which contains stain 

 but no atropine, no amoeboid movements will occur, 

 and the cells retain their spherical shape. If the jelly 

 is neutral, however, occasionally sluggish movements 

 occur, even at the room temperature. At a tempera- 

 ture of 30 to 37 C. sluggish movements may occur 



1 The alkalinity oHhese jellies is not sufficient to precipitate the alkaloids. 



