W. J. CROZIER 



729 



3. Anesthetics. 



Ether, ethyl alcohol, chloroform, and MgS04 all produce a very- 

 decided increase in the apparent time of penetration of acids. 



Experiment 8.54.1. — Tissue from several animals of the same size; acid, 0.05 N 

 HCl. Pieces of mantle immersed for the intervals stated in sea water containing 

 M ethyl alcohol, then transferred to acid. 



A number of tests shov^ed essentially similar conditions under the 

 action of other anesthetics. The primary effect of these materials 

 is to decrease the penetrability of the tissue toward acids. Ether, 

 one-half saturated in sea water, and chloroform, one-fifth saturated, 

 decreased the apparent penetration rate of even 0.1 n HCl by 50 

 per cent, in 2 minutes and in 5 minutes respectively. 



4. Pigment Diffusion. 



The outward diffusion of intracellular coloring matters has 

 frequently been employed as a criterion of increased permeability 

 to the pigment involved, and by inference to other substances also. 

 In addition to other sources of error, this method of observation 

 tends to ignore the fact that the pigment concerned may be held in 

 the cell, not by the state of the cell surface primarily, but by the 

 relation of the pigment, especially when in the form of droplets, 

 to the cytosome as a whole. 



As bearing upon the value of pigment diffusion as an index of 

 permeability increase, I would cite experiments showing that the 



