OF VITAL PHENOMENA 127 



— .198 T 2 , which means that a thermocurrent will be produced 

 proportional to the difference in absolute temperature. Bern- 

 stein found this to be true also, the warmer end being positive. 



Further proof of functional change in permeability of the 

 plasma membrane to electrolytes was found on measuring the 

 conductivity of sea urchin eggs by the Kohlrausch method. The 

 conductivity increases when the eggs are stimulated to begin 

 development (McClendon, 1910 c, e). This was confirmed by 

 Gray (1913, a, b) who observed an increased conductivity in the 

 first fifteen minutes of development. Just what electrolytes were 

 affected by this increase in permeability was not ascertained, but 

 in case of the frog's tgg, the author was able to show an in- 

 creased permeability during the first hours of development to 

 Na, K, Mg, Ca, and CI (1914 a, 1915 a). The eggs were caused 

 to develop in distilled water by means of electric stimulation, and 

 the salts which diffused out analyzed and compared with those 

 diffusing out of unstimulated controls. 



A change in permeability may also accompany pathological 

 changes. It was shown (McClendon, 1913 a, 1914 c) that the 

 eggs of certain fish which are impermeable both to water and 

 to salts, may be made permeable to salts by various toxic sub- 

 stances. Salts diffuse out of these poisoned fish into the distilled 

 water in which they are placed, and (possibly as a result of in- 

 creased permeability) they develop into monstrosities. An in- 

 crease in permeability to water was shown by Loeb (1912 b). 



If stimulation means increase in permeability, we should ex- 

 pect anesthetics to prevent it, since they prevent response to 

 stimuli. It was observed that the increase in permeability of 

 the eggs of certain fish to electrolytes could be partially inhibited 

 by ether (McClendon, 1914 b, 1915 b). 



Since Kite claims that the interior of the cell has the same 

 permeability as the surface, it is probably worth while to empha- 

 size that the effect of temperature change on the emf of the 

 current of injury furnishes evidence that the seat of restricted 

 permeability is the uninjured cell surface. Furthermore, Hober 

 (1910 a, 1912 b, 1913 b) has shown that the electric conductivity 

 of the interior of the cell is greater than that of the whole cell, 

 including the plasma membrane. 



