BIOLOGICAL SIGNIFICANCE OF ADSORPTION 1 59 



The Biological Significance of Selective Adsorption. 



BY JEAN DUFRENOY. 



Modern biologists come more and more to view living matter in 

 the light of colloid complexes, of which those constituting nucleo 

 and cytoplasma may be termed "cyto-coUoids," whereas those 

 building cell-walls or intercellular spaces may be named "histo- 

 collolds." 



Adsorption is a most important property of colloids. Adsorption 

 indeed, is most satisfactorily explained as a concentration of a 

 solute at a surface, and colloids ojEfer much useful surface. 



Certain surfaces not only have the power of adsorbing a solute 

 as a whole from solution, but have the power of adsorbing a part 

 of a solute at a greater rate than the other. 



That an ion may be thus selectively adsorbed from an electrolyte, 

 concomitant or previous hydrolysis of the electrolyte is of course 

 necessary. 



Living matter being colloidal, is possessing selective adsorbing 

 properties, which may tentatively furnish an explanation of the 

 metabolic processes in the living being, and of the migration of 

 solutes into the cells, or of the color reaction of the tissues. 



A most convenient biocolloid to experiment on, was furnished 

 to us by the mucous deposits in. the thermal springs of Bareges 

 (Pyrenees). These deposits long known as "Baregine" are zooglae 

 secreted by various Bacteriacea. True Baregine, as defined by us, 

 is a furfuroid, soluble in xanthogenate reagents, as distinguished 

 from the cell wall proper of the Bacteria, which is made up of 

 nonsoluble chitin-like material. [8, 11.] 



I. — Basophilous Adsorption. 



Many vegetable histo-colloids have a superior adsorbent capacity 

 for bases, and redden blue litmus, (which is a salt, containing a 

 strong base, while the acid is the red dye itself.) 



This reddening is easily observed in the case of Baregine by the 

 following experiments : (i.) Blue litmus which is made to filter 

 through a plug of Baregine, first filters red, and later on filters 

 uncolored. (2) Blue litmus, kept in a glass tube above a plug 

 of Baregine, reddens, and in a few hours loses its color from its 



