Mat 26, 1916] 



SCIENCE 



751 



NaCl, a markedly decreased resistance, and 

 after exposure to solutions of CaCl,, a mark- 

 edly increased resistance, at least for a short 

 period; but there was no appreciable variation 

 from the normal after exposure of the tissues 

 to mixtures containing NaCl and CaCl^ in the 

 ratios of 100 molecules of the former to one 

 or two of the latter. Osterhout concluded as 

 a result of these and other experiments that 

 electrolytes may be divided into two main 

 antagonistic groups according to whether they 

 raise or lower the permeability of the proto- 

 plasmic membrane. 



The ratio of 100 molecules of NaCl to 1 or 2 

 molecules of CaCl, is one of peculiar signifr 

 icance in biology. ISTaCl and CaCl, occur in 

 approximately this ratio in sea-water, the 

 blood of mammals, and other saline media 

 capable of supporting life. Furthermore, ma- 

 rine organisms are killed by transference to 

 artificially prepared solutions of NaCl or 

 CaCl, isosmotic with sea-water, but they re- 

 main uninjured if transferred to a solution of 

 NaCl to which enough CaOl, has been added 

 to give the ratios in question. 



The writer's experiments on emulsions start 

 from an observation made by Bancroft that 

 soaps of E'a, used as emulsifying agents for 

 oil and water, give an emulsion consisting of 

 drops of oil dispersed in water like cream, 

 while soaps of Ca exert the reverse effect, pro- 

 ducing emulsions consisting of drops of water 

 dispersed in oil like butter. The writer be- 

 lieved that these experiments might offer a 

 physical explanation for the antagonistic 

 effects exerted by salts of ISTa and Ca on one 

 another, not only in biological systems of the 

 type described above, but also in such purely 

 physical processes as blood coagulation and 

 the production of a casein clot. In the coagu- 

 lation processes in question the transforma- 

 tion of a suspension of a protein dispersed in 

 water, into a clot in which water is more or 

 less dispersed in an outer or continuous pro- 

 tein phase is promoted by salts of Ca and in- 

 hibited or retarded by alkalies and salts of 

 ISTa. Therefore the first question to determine 

 was -vdiether a similar transformation could be 

 effected in the ease of emulsions. In the pre- 



liminary paper referred to above the writer 

 was able to demonstrate that suitably consti- 

 tuted emulsions of oil dispersed in water could 

 be converted into emulsions of water dispersed 

 in oil by shaking with salts of Ca, and that 

 the transformation in question could be pre- 

 vented, or a reverse transformation effected, by 

 shaking with an adequate proportion of WaOH. 

 It was subsequently demonstrated that ISTaCl, 

 and other salts of ISTa, exert an effect on emul- 

 sion systems similar to that of NaOH but 

 considerably weaker. The processes of blood 

 coagulation and emulsion transformation ap- 

 pear to be similar physical effects promoted by 

 salts of Ca and inhibited by alkalies and salts 

 of Na. In both cases, a system consisting of 

 a non-aqueous phase dispersed in water is con- 

 verted, more or less perfectly, into a system 

 consisting of water dispersed in the non- 

 aqueous phase, analogous to the transforma- 

 tion of islands surrounded by water into lakes 

 surrounded by land. It is obvious that a sys- 

 tem of islands surrounded by water is freely 

 permeable to water and water-borne sub- 

 stances, while a system of lakes surrounded by 

 land is absolutely impermeable. A variety of 

 intermediate systems exhibiting any desired 

 degree of permeability can well be conceived. 

 Since salts of Ca promote a transformation in 

 one direction and alkalies and salts of Na in 

 the reverse direction, it appears probable that 

 by simply varying the proportions of the salts 

 in question introduced into a given system 

 it should be possible to vary the permeability 

 of the system to water to any desired extent. 

 Since variations in the permeability of proto- 

 plasm induced by variations in the proportions 

 of salts of Ca and l!fa appear from Osterhout's 

 experiments to account for the destructive 

 effects exerted by salts of Ca and ISTa when 

 used individually, and the protective effect 

 exhibited when these substances are used 

 jointly in ratios of 100 molecules of NaCl to 

 1 or 2 of CaCl„, the question arises how far can 

 such a mechanism as that described above in 

 the case of emulsions and blood coagulation 

 explain protoplasmic structure and function! 

 From what we know of protoplasm and the 

 protoplasmic film it is by no means incon- 



