140 



W. J. V. OSTERHOUT 



been enabled to carry out a large number of quantitative re- 

 searches some of which are briefly summarized in the following 

 paragraphs. 



The first of these relates to alterations of permeability. 



According to one opinion permeability is a relatively fixed 

 property of the cell and is altered only as the result of injury: the 

 alteration is then irreversible. 



Another view assumes that there are reversible changes in 

 permeability which involve no injury and which may form a 

 normal part of the activities of the cell. If such changes occur 

 it is clear that they may control the course of metabolism. 

 That permeability may be altered in this manner is suggested by 

 a number of facts, but their interpretation is too doubtful to 

 place this view on a firm basis. It is highly important that its 

 truth or falsity be established by rigorous proof. Such proof 

 seems to be afforded by a series of experiments, some of which 

 have recently been described.^ 



Upon transferring the living tissue from sea water to pure 

 sodium chloride of the same conductivity (and at the same 

 temperature) an immediate increase of conductivity was ob- 

 served, which up to a certain point proved to be reversible. 



In order to make certain that no injury resulted from a brief 

 treatment with sodium chloride an experiment was performed to 

 ascertain the effect of repeated treatments on the same lot of 

 tissue. In one experiment the tissue was treated with sodium 

 chloride until the resistance dropped from 1020 ohms to 890 ohms 

 and was then replaced in sea water, after which the resistance 

 rose to 1020 ohms; this was repeated daily on the same lot of 

 tissue for fifteen days. On the tenth day the tissue began to show 

 a falling off in resistance, which continued to the fifteenth day, 

 when the experiment was discontinued. As this falling off was 

 also shown by the control, which was kept in sea water throughout 

 the experiment, it was not due to the sodium chloride, but to other 

 causes. 



Electrolytes may also cause a reversible decrease in permeabil- 

 ity. The simplest way of demonstrating this is by adding to the 



•Science N. S. 36: 350, 1912. 



