Abstract
The penetration of 2,- 6,- dibromo phenol indophenol into Valonia was observed when the external pH was varied from 5 to 9, and when the internal pH was changed from normal (6.4) to 5.2 and to 9.0. It was found that when the pH of the sap was normal, the penetration of the dye into the sap follows the course of a bimolecular reaction curve, and the amount of dye in the sap at equilibrium is proportional to the amount of undissociated dye in the external solution. When the sap is made more acid than normal, there is more dye present; when the sap is more alkaline there is less dye present. At higher temperature and lower concentrations, the curves follow a course like that for two consecutice unimolecular reactions. 2,- 6,- dibromo phenol indophenol was found in the sap only in a completely reduced form. Its concentration was estimated colorimetrically after it had been reoxidized in vitro.
Methylene blue was found to penetrate into the sap in an oxidized form. This dye is a very strong base and is completely dissociated at all pH values used in these experiments. The amount found in the sap did not vary with external nor with internal changes in pH from 5 to 9.
K-indigo tetrasulphonate was found to penetrate into the sap in a yellow form.
K-indigo disulphonate could not be found in the sap by means of the method used.
The electrode potential or Eh of the protoplasm was tentatively found to be between .21 and .48 subject to certain assumptions. The Eh of the sap was found to be between .12 and .15, subject to certain assumptions. By further calculations, the rH or the logarithm of the reciprocal of the hydrogen pressure of the sap was found to be between 16 and 18; that of the protoplasm was less exactly defined.
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