experiments on the exit of brilliant cresyl blue from the living cells of nitella , in solutions of varying external ph values containing no dye , confirm the theory that the relation of the dye in the sap to that in the external solution depends on the fact that the dye exists in two forms , one of which ( db ) can pass through the protoplasm while the other ( ds ) passes only slightly .
C0007634
cells
C0175996
protoplasm