THE PERMEABILITY OF CELLS 519 



The acid solutions contained y/oo HCl; the alkahne Ywoa 

 NaOH in tap water; neutral solutions were of glass distilled water. 

 The acid had no effect on the Spirogyra during the short time 

 of the experiment, under four hours. The dyes (all prepared by 

 Griibler and Co.) were of such concentration as to give a very 

 light colored solution in a layer 3 cm. thick. Many dyes cannot 

 be satisfactorily studied because they become colorless very 

 rapidly in alkaline solution and less rapidly in neutral solution. 

 The letter B in the next table placed after the dye signifies that 

 it is basic; A signifies an acid dye. In the last colunm is given 

 the stainable power of the yolk platelets of the frog's egg in the 

 same dilute dye solutions used in the study of Spirogyra. The 

 platelets were obtained from the ovarian eggs of Rana catesbiana. 

 They are regarded by McClendon ('10) as a lecithalbumin 

 ''composed of 6 per cent lecithin and 94 per cent batrachiolin, a 

 nucleo-albumin containing 1.2 per cent phosphorus, 1.3 per cent 

 of sulphur, and 15 per cent of nitrogen." 



The entrance of all the basic dyes studied is indicated in 

 Spirogyra by precipitation with tannic acid as fine colored gran- 

 ules, just as is neutral red. On the contrary the penetration of the 

 acid dyes is accompanied by a combination of the dye with the 

 cell proteids, nucleus and pyrenoids appearing colored first, then 

 cytoplasm and chlorophyll bands. The spiral bands are often 

 distorted, the nucleus swollen and turgor is invariably lost. This 

 is true of all the acid dyes given in the following table and is indi- 

 cated by the word stained. As mentioned above the appearance 

 of cell staining is often given by a union of the dye with the cellu- 

 lose wall but this is readily detected by high magnification. It 

 is obvious that only the presence of colored granules in the sap 

 vacuole or the staining of the protoplasm should be regarded as 

 criteria of permeability. 



2. Relation to Overton's lipoid theory 



It will be seen from table 1 that it is the free color bases or acids 

 which enter cells and not their salts and this is the same result 

 which Robertson obtained in studying the solubility of dyes in 



