EALPH S. LILLIE 791 



exhibit such a remarkable parallelism with physiological antagonisms, 

 are referable to the formation of soaps or soap-like compounds. 

 It seems probable that variations in the partition of such compounds 

 between the aqueous and the non-aqueous or organic solvents of 

 the protoplasm are important factors in the physiological effects 

 produced by varying the proportion of the inorganic salts in the 

 medium. Clowes attributes the variations in the drop numbers 

 of the solutions flowing through the oil from the stalagmometer 

 to variations in the ratio of the oil-soluble to the water-souble soaps. 

 These soaps have opposite influences on the surface tension factor 

 opposing the detachment of the drop. Oil-soluble compounds like 

 higher alcohols influence the drop numbers in the same manner as 

 Ca salts. The recent observations of Heilbrunn^^ on changes in pro- 

 toplasmic consistency under the influence of lipoid-solvent compounds 

 also suggest that variations in the partition of compounds between 

 the aqueous and the lipoid phases of protoplasm may influence 

 greatly the type of protoplasmic consistency or structure. 



Jn general, it may be inferred from the above facts that the presence 

 of a certain proportion of solid water-insoluble salt-like compounds 

 in the protoplasmic surface film is necessary to the normal semi- 

 permeability and structural permanence of this structure; similar 

 considerations apply to filamentous solid structures like cilia and 

 to the other solid structural elements of the cell. This view explains 

 the destructive action of pure solutions of alkali salts like NaCl, 

 which have the effect of substituting water-soluble Na-compounds 

 for the water-insoluble Ca compounds {e.g., soaps) normally present. 

 Hansteen's^ results with plant tissues afford strong evidence that 

 water-insoluble Ca compounds are essential to the stability of the 

 normal protoplasmic structures, and also of cell walls and similar 

 structures formed by protoplasmic activity. He attributes great 

 importance to lipoid compounds present in the protoplasmic sur- 

 face layers and in the cell walls, and especially to the formation of 

 water-insoluble combinations between these materials (together with 

 pectin) and calcium. He regards these calcium compounds as nec- 

 essary for the normal coherence of cells, as shown by their presence 



18 Heilbruim, L., Biol. Bull., 1920, xxxix, 307. 



