W. J. V, OSTERHOUT 411 



One of the most striking results observed in studying the electrical 

 resistance of Laminaria is the fact that some substances (as CaCl2) 

 decrease permeability while others (as NaCl) increase it. It is of 

 interest to see whether animal tissue behaves in the same manner. 



When Laminaria is placed in a solution of CaCL (of the same con- 

 ductivity as the sea water) the resistance^ rapidly rises, often as much 

 as 65 per cent; in LaNOs it rises even higher (90 per cent or more),« 

 while in MgCl2 the rise is less (up to 10 per cent). The rise is suc- 

 ceeded by a fall, which continues until death. The resistance has then 

 dropped to about 10 per cent of the normal resistance.^^ 



When frog skin is placed in CaCl2 of the same conductivity as 0.2 

 sea water (about 0.056 m CaCl2), the resistance rises rapidly, just as 

 in the case of Laminaria, though not as high (up to 40 per cent). It 

 then begins to fall, and continues to do so until the death point is 

 reached^i at about 10 per cent of the normal resistance. In LaNOs 

 the rise is greater (up to 90 per cent) , and in MgCl2 it is less (up to 10 

 per cent). It will be seen that the behavior of frog skin toward these 

 agents closely resembles that of Laminaria. 



Acid (HCl) causes a rapid rise of resistance in Laminaria, '^'^ followed 

 by a rapid fall. This is also the case with frog skin placed in a solu- 

 tion of HCl of the same conductivity as 0.2 sea water (about 0.024 m 

 HCl) or in this solution diluted with 0.2 sea water. The use of 

 HCl is attended by some complications which will be discussed in a 

 later paper. 



There is another group of substances, such as NaCl and KCl, which 

 produce no rise in the resistance of Laminaria. On transferring tissue 

 from sea water to solutions of these substances (of the same conduc- 

 tivity as sea water) there is a fall of resistance which continues until 

 the death point is reached. The same is true of frog skin (using 0.2 

 sea water) except that the fall of resistance is much slower than in the 

 case of Laminaria. It is, however, completely paralleled by the slow 

 fall of resistance found in some other plant tissues, such as those of 

 the dulse {Rhodymenia palmata).^ 



8 Osterhout, W. J. V., Bot. Gaz., 1915, lix, 317. 



9 Osterhout, W. J. V., Boi. Gaz., 1915, lix, 464. 



^^ The resistance of the apparatus is subtracted in all cases. 

 ^^ The death point is not so well defined as with Laminaria. 

 12 Cf. Osterhout, W. J. V., /. Biol. Chem., 1914, xix, 493. 



