412 PERMEABILITY IN PLANT AND ANIMAL CELLS 



In mixtures of NaCl and CaCl2 in suitable proportions^' Laminaria 

 remains alive longer than in pure NaCl or in pure CaCl2. This is also 

 true of frog skin, although the result is not as marked as in the case 

 of Laminaria; this is perhaps due to the fact that NaCl is less toxic to 

 frog skin. 



Of special interest is the behavior of anesthetics. In the case of 

 Laminaria they produce two effects, a reversible (anesthetic) action 

 consisting in a decrease of permeability and an irreversible (toxic) 

 action consisting in an increase of permeability.^'* On placing tissue 

 in sea water containing suitable amounts of ether (1 per cent), chloro- 

 form (0.1 per cent), or chloral hydrate (0.1 per cent), the resistance 

 rises and this condition is maintained for some time. With increas- 

 ing concentration a point is soon reached at which the resistance rises 

 rapidly to a maximum and then falls rather rapidly. When it has 

 fallen below the normal there is little or no recovery on replacing it in 

 sea water. With alcohol such recovery is possible. 



The same is true of frog skin (using 0.2 sea water) but the effect is 

 even more striking, the rise of resistance being greater and occurring 

 at lower concentrations. In respect to recovery we find the same 

 difference between ether, chloroform, and chloral hydrate on the 

 one hand and alcohol on the other. 



The method of measuring electrical resistance enables us to study 

 the dynamics of the death process. It his been shown that when 

 Laminaria dies in a solution of NaCl the process follows more or less 

 closely the curve of a monomolecular reaction. ^^ The same is true 

 of frog skin. In both cases we are led to the assumption that the 

 process of death is one which is always going on during the normal 

 life of the cell and that it is accelerated by the toxic agent. It is also 

 found, in both Laminaria and frog skin, that if the death process has 

 not proceeded too far a complete or partial recovery is possible when 

 the tissues are removed from the toxic solution and returned to sea 

 water (or 0.2 sea water). 



In both cases it appears that permeability is a delicate and accurate 

 index of the vitalityi^ of the protoplasm and that agents which pro- 



'3 Osterhout, W. J. V., Proc. Am. Phil. Soc, 1916, Iv, 533. 

 " Osterhout, W. J. V., Bot. Gaz., 1916, ki, 148. 

 15 Osterhout, W. J. V., /. Biol. Chem., 1917, xxxi, 585. 

 i« Osterhout, W. J. V., Science, 1914, xl, 488. 



