l6o THE AMERICAN' MIDLAND NATURALIST 



contact to the Baregine upwards. In both cases, adsorption is 

 selective at first, and total ultimately. 



2. — Consequences of Basophilous Adsorption. 

 There is a struggle for bases constantly going on between baso- 

 philous colloids in the plant and those in the habitat. This is 

 most conveniently studied in the cases of unicellular plants: 

 Iron-bacteria, Diatoms, but it is as important for flowering plants 

 in the field. But even the different parts of the same plants struggle 

 for bases, and this should be studied first. 



I . — Metachromasia. 



Many blue dyes are salts, containing colored base and aeid 

 radicals. Either the base or the acid, when free, may be itself a 

 red dye. 



Whenever basophilous substances are in contact with these 

 blue salts containing a red free base, they color red, by adsorbing 

 the red base. 



The red color displayed by colloids bathing in blue solutions 

 is termed metachromatic. 



Therefore, most cases' of metachromasia readil)^ explain 

 by selective adsorption, and we actually observed substances 

 which color metachromatically to be basophilous: For instance, 

 such zooglse in the Baregine, which adsorb Fe or Cu as bases from 

 their salts, also color red by basic blues (Naphtylen blue, Methylen 

 blue.) 



The same explanation no doubt holds for cyto-colloids ; and the 

 so called "metachromatic granules" in the cells certainly are 

 basophilous gels (or maybe sols). Indeed, metachromatic granules 

 were artificially produced, where metachromasia is the result of 

 selective basophilous adsorption: A drop of a xanthogenate 

 (obtained by dissolving Baregine into CS2+KOH mixture) being 

 placed in contact with a drop of aqueous solution of naphtylen 

 blue or Polychrome blue, it appears an emulsion of tiny red granules, 

 exactly alike the metachromatic granules in the cells. 



Metachromatic granules are conspicuous substances in the cell, 



' Some cases may result of different colors displayed by the same solute 

 as its solvent changes, as assumed by Moreau.^ In fact, we found the 

 "insoluble blue acid of the^Congo, to yield a red solution in Amylic alcohol. 



" F. MoREAU, Sur les pheno. de metachromasie : Bull. Soc. hot. France, 

 t. 63, p. 72, 1916. 



