MECHANISM OF PEOCESS OF DEATH 55 



These results present a marked contrast to those 

 obtained by the use of alkali ; with the latter there is no 

 rise in resistance, but, on the contrary, a fairly rapid 

 fall which continues until the death point is reached. 



In view of the great importance of acid and alkali in 

 life processes these results deserve especial consideration 

 since it would seem that slight changes in the reaction of 

 the medium affect conductivity and permeability. 



It may be added that experiments with frog skin^^ 

 showed that in this case also HCl produces a rapid rise 

 in resistance followed by a fall. Shearer (1919, A) found 

 a rise in the case of bacteria. 



The writer has also found^* that high concentrations 

 of KCN (0.01 to 0.381 M) produce a slight temporary 

 rise in the resistance of Laminaria.^ 



It is of considerable interest to find that certain 

 organic substances are able to increase resistance. As 

 an example of this we may consider experiments with 

 bile salts.^" In these investigations Na-taurocholate was 

 added to the sea water, which was then restored to its 

 normal conductivity and made approximately neutral 

 to litmus.^'' All concentrations employed produced an 

 immediate increase in resistance followed by a fall, 

 as illustrated in Fig. 26. Under the conditions of the 

 experiment, the rise lasted about an hour. An increase in 

 resistance was also observed with TJlva rigida (sea 



'^Cf. Osterhout (1919, 0). 



"Osterhout (IfllT, A). 



"Possibly this might have been greater had not the solution 

 been alkaline. 



^Osterhout (1919, B) . 



" The amounts varied from 0.8 to 1.5 gm. added to 1000 c.c. of sea 

 water. If the Na-taurocholate were pure 1 gm. in 1000 c.c. would make 

 the concentration about 0.002 M, but its purity is doubtful. 



