132 PHYSICAL CHEMISTRY 



on death — hence, electroendosmose must be reduced or cease 

 also. The cause of this cessation of electroendosmose at death 

 is probably not a sudden abolition of the difference in concentra- 

 tion of ions causing the emf, but an alteration of the membrane. 

 It was shown long ago by Nageli, and repeatedly confirmed by 

 others, that increase in permeability of the plasma membrane 

 is so intimately associated with death of the cell that the two 

 phenomena are probably the same thing. This seems true not- 

 withstanding the fact that the plasma membrane may not lose 

 all of its semipermeable properties on death. Some of the evi- 

 dence that disappearance of the bioelectric phenomena alter os- 

 mose are as follows : 



If the turgor of living cells is due to electroendosmose, dead 

 cells should dry in air sooner than live ones. This fact is the 

 teleological principle involved in the instinct of certain wasps 

 who store spiders with the eggs so that the larvae may have food. 

 If the spiders are killed they dry up before the eggs hatch, hence 

 the necessity of keeping them alive. The wasp stings the spider 

 in its central nervous system so that it remains alive in a paralytic 

 condition. Bernstein ("Elektrobiologie") tied living and dead skin 

 over the mouths of two tubes filled with water. The evaporation 

 took place more rapidly through the dead skin. He suspended 

 two similar pieces of the frog's skin from the two arms of a 

 balance. One of the pieces of skin was killed, and it then lost 

 weight faster than the other. A similar experiment with plant 

 leaves gave the same result. The same was true of frog's muscle 

 if the experiment were terminated within a half hour, at the end 

 of which time the live muscle had been killed by drying. 



Recent experiments by F. H. Scott on blood volume and by 

 A. D. Hirschfelder on edema confirm the older ideas that the 

 transfer of fluid in the mammalian body is largely accounted 

 for by filtration and the osmotic pressure of colloids. The 

 osmotic pressure of colloids is considered in Chapter VI. 



