\V. J. CROZIER 731 



criminately to all classes of substances, the facts already enumerated 

 make it hazardous to lay much weight upon pigment diffusion as an 

 index of permeability changes (Crozier, 1916 b). Thus in LiUie's 

 extensive operations with Arenicola larvae (1913), the fact that in 

 the presence of anesthetics pigment diffusion is retarded, has been 

 urged as evidence for the restraint by anesthetics of permeability- 

 increasing agencies; on the other hand, when mantle tissue of 

 Chromodoris is subjected to the action of anesthetics, pigment is 

 lost much more readily than otherwise, even though the resistance 

 of the tissue toward the diffusion of acids is by this action markedly 

 enhanced. 



SUMMARY. 



The penetration of acid into mantle tissue of Chromodoris zebra 

 is accelerated after local faradic stimulation, and is retarded by 

 brief treatment with anesthetic solutions. The spontaneous out- 

 ward diffusion of intracellular pigment is an inadequate criterion of 

 "permeability." Outward diffusion of pigment and penetration 

 of acid are both facilitated when the tissue is artificially put under 

 tension. 



BIBLIOGRAPHY. 



Carlson, A. J., 1907, On the mechanism of the stimulating action of tension on the 

 heart, Am. J. Physiol., xviii, 149. 



Crozier, W. J., 1916, a, Cell penetration by acids, /. Biol. Cheni., xxiv, 255. 



Crozier, W. J., 1916, b, On loss of cell pigment as an index of permeability changes, 

 Science, xliii, 145. 



Lillie, R. S., 1909, On the connection between changes of permeability and stimula- 

 tion, and on the significance of changes in permeability to carbon dioxide, 

 Am. J . Physiol., xxiv, 14. 



Lillie, R. S., 1913, Antagonism between salts and anaesthetics, — III. Further 

 observations showing parallel decrease in the stimulating, permeability in- 

 creasing, and toxic actions of salt solutions in the presence of anaesthetics, 

 Am. J . Physiol., xxxi, 255. 



