dealing ivith the Phenomena of " Clot " Formations. 371 



surface tension. The viscosity of salt solutions also probably plays some 

 part in that disaggregating action of salts which is connected with their 

 effect on surface tension of water, owing to their forming a kind of diffusion 

 layer round the colloid phase. This action has been already discussed in 

 some detail in an earlier paper.* 



VL Influence of Salts due to Differences in Diffusion Bates. — Salts will 

 diffuse from one phase to another at different speeds, and the rate of inter- 

 change between the phases will be a function of this factor, which is such an 

 obvious one that it needs no detailed discussion. It is possible that salts 

 also exert other actions which have not been enumerated here. 



From the foregoing remarks it would appear probable that the action of 

 salts in a gel system is very complex and that it is hardly possible to 

 investigate each single factor in a system such as that of the cholate gel ; the 

 results recorded in this paper must, therefore, be regarded as somewhat 

 empirical in character. In this and in the earlier papers of this series on gel- 

 formation, attention has been repeatedly drawn to the analogies between the 

 physical characters of the cholate gel and certain vital activities of the cell, 

 and if, as has been suggested, the protoplasm and the cell membrane contain 

 a gel structure like that of the cholates, it is obvious that the biological action 

 of salts must be a very complex one, which cannot be ascribed to the action 

 of any one single factor acting separately. It is hoped that by a continuation 

 of this work more light may be thrown on certain important physiological 

 problems, especially those connected with the permeabilities of cells and 

 their functional changes. Attempts have already been made to trace further 

 analogies between the action of salts in producing such changes and their 

 erosive action on cholate gels. 



Summary. 



1. The erosive action of chloride solutions on a cholate gel containing 

 added chlorides has been investigated. If the concentrations of the eroding 

 solutions are plotted as abscissa? and the amounts of erosion as ordinates, a 

 curve is obtained which is of diphasic character. The amount of erosion 

 increases with increasing concentration to a maximum, and then, with 

 further increase in the concentration of the eroding solution, it diminishes to 

 a minimum; on increasing the concentration beyond this latter point, the 

 amount of erosion increases continuously. The portion of the curve between 

 the two minimal points is designated the " zone of instability " of the gel. 



2. The breadth of this zone and the amount of erosion within it is a 



* Schryver, ' Eoy. Soc. Proc.,' B, vol. 83, p. 96 (1910). See also Traube, ' Inter - 

 nationelle Zeitsch. f. physikalisch-chemische Biologie,' vol. 1, p. 275 (1914). 



