46 INJUEY, EECOVEEY, AND DEATH 



and trivalent still more so.^* In most cases the effect is so 

 striking that the addition of the solid salt to the sea 

 water, although decreasing the resistance of the solution, 

 nevertheless increases the resistance of the living tissue 

 so greatly that the net result is an increase in the resist- 

 ance of the tissue plus solution. As this does not happen 



§ 



80-t 







20 HOURS 40 



FiQ. IS. — Curve showine the net electrical resistance of Laminaria'agardhii in sea water to 

 which was added sufficient cobalt chloride (in the form of dry salt) to make the concentration 

 0.005 M. Solution neutral to litmus. All readings were taken at 18° C. or corrected to this 

 temperature. The ourve represents a single experiment. Dead tissue showed no rise. 



with dead tissue the increase must be due to an alteration 

 in the living protoplasm.^* It is therefore evident that 

 the current must flow in part through the living proto- 

 plasm^ as well as through the cell walls. 



In the case of certain bivalent kations (Mn, Co, Cd, Ni, 



"C/. Osterhout (1915, E). 



" It might te suggested that the increase in resistance is due to a de- 

 crease of the spaces between the protoplasmic masses brought about by an 

 expansion of the protoplasm or by a shrinkage of the cell wall. Micro- 

 scopic and macroscopic examination shows that this does not occur. The 

 tendency is, on the other hand, to increase the spaces between the cells, 

 as the result of incipient plasmolysis. 



When dead Laminaria is transferred from sea water to CaCl, 0.278 M 

 there is a very slight shrinicage which, however, is entirely inadequate to 

 cause a noticeable rise in resistamse if it occurs in the cell walls of 

 livuag tissue. 



