DEPARTMENT OF BOTANICAL RESEARCH. 61 



cell with colloidal walls the ensuing endosmose or amount of water pulled 

 through the wall is widely disproportionate to the calculated osmotic activity 

 of the kations. A calcium solution with an osmotic value of 40 as compared 

 with that of potassium at 28 shows an endosmose of 12 as compared 

 with that of potassium at 60. A similar relation is shown when potas- 

 sium calcium is placed in the immersion fluid of cells with contents, such 

 as sugar, with superior osmotic concentration. The cell in potassium takes 

 in more water than the one in calcium. The potassium would therefore 

 appear to modify the membrane in such manner as to make it less permeable 

 to sugar as well as to its own kations, while the calcium would have the 

 reverse effect at the concentrations tested. This would also apply to living 

 cell-masses of Rubus. 



The external layer of the living and of the artificial cells in these cases 

 appears to become a better osmotic membrane under the action of agencies 

 which would increase hydration of the pentosanic component. That the 

 increased hydration of an agar layer would not make it a more efficient 

 membrane in osmosis is clear. It would appear, therefore, that the phenom- 

 ena in question must be referred to the lipoid layer, and that when this layer 

 is defective or slight, effects such as those shown by the walnut may be 

 expected. The solutions of calcium used are known to cause a precipitation 

 or aggregation of such lipins as lecithin, and this transformation would increase 

 the permeability of the layer to kations, while the liquefaction of the layer 

 would result from the action of potassium. 



Much greater changes would result in both the living and the artificial 

 cell than ones of simple hydration or coagulation. The action of any of these 

 reagents which seriously alters the state of any one of the components of the 

 heterogeneous system might be expected to cause partial or complete reversals 

 of phase in the colloidal material, and such changes as suggested by Clowes 

 might well be of such importance as to cause wide or abrupt changes in per- 

 meability. This author lays great stress on the action of soap films in hetero- 

 geneous systems. It is not clear that the existence of such films in plant 

 cells could be safely predicated in view of their relatively high acidities in 

 which they could not exist. Great variations in acidity may take place 

 without corresponding alterations in permeability. At the same time it is 

 to be noted that the presence of such fatty substances as the lipins in a two- 

 phase condition, enmeshed with pentosans and possibly proteins, would make 

 a heterogeneous system in which reversals of phase would entail wide varia- 

 tions in permeability. 



The external layers of the cell, which are exemplified by the artificial cell 

 used in these experiments, may be considered as a heterogeneous colloidal 

 system in which the pentosans and lipins are the most important constituents. 

 The kations of the ordinary bases of importance to the plant modify the 

 hydration of the pentosans at the concentrations ordinarily encountered. 

 These substances are seen to cause still more marked changes in the hydra- 

 tion of lipins, the reactions including flocculation or precipitation. Changes 

 of this character would include reversals of phase and abrupt modifications of 

 conductivity. 



Interferences or "antagonisms," particularly between those which exert a 

 .strong effect on colloidal state and those which are less active, have been 



