no 



Scientific Proceedings (91). 



to an extraordinary degree with data previously accumulated by 

 the writer by means of the capillary pipette drop method regarding 

 the influence exerted by NaCl, CaCl 2 , etc., on soap films and 

 surface tension. These conductivity and filtration experiments 

 taken in conjunction with the recently published filtration experi- 

 ments of Hirschfelder and the writer's previous experiments with 

 soap films and emulsions lend strong support to the contention 

 previously advanced by the writer that variations in the permea- 

 bility of the protoplasmic membrane are attributable to the action 

 of electrolytes and metabolic products on delicately balanced inter- 

 facial soap films and emulsion systems and that proteins may play 

 no part in the valve-like mechanism controlling permeability other 

 than to afford a supporting filamentous or mesh-like structure. 



Further support of this point of view is found in the fact that 

 when blood plasma is clotted by the addition of CaCU no con- 

 siderable change in electrical resistance is noted while in the trans- 

 formation of an emulsion of oil in water into one of water in oil 

 by shaking with CaCl 2 the resistance suddenly rises to an enor- 

 mous extent at the critical point at which oil becomes the con- 

 tinuous or external phase. 



It is obvious, therefore, that while the clot or jelly formed from 

 fibrinogen is almost as freely permeable to water as the original 

 plasma, the emulsion under similar conditions has been converted 

 from a system which is freely permeable to one which is absolutely 

 impermeable to water. Any intermediate degree of permeability 

 is theoretically obtainable, providing the working conditions are 

 sufficiently delicate. Since the main factor involved is that of 

 surface tension, a finely dispersed emulsion structure contained 

 in the capillary spaces of a jelly or its filter paper analogue would 

 obviously respond with far greater delicacy to those substances 

 which promote or inhibit permeability than would an emulsion 

 in gross form. Since the whole question resolves itself, apparently, 

 into one of the state of dispersion of soaps it is obvious that the dis- 

 persing effects exerted by NaCl on soap films and the consequent 

 considerable lowering of the surface tension of the water phase and 

 promotion of the permeability of the emulsion which have 

 already been demonstrated in previous communications by means 

 of the capillary pipette and other methods would be even more 



