116 SOME RECENT RESEARCHES IN PLANT PHYSIOLOGY 



too, when added in the solid condition to sea-water, greatly 

 increases the resistance of protoplasm, although it decreases 

 that of the water. 



As pointed out in connection with the plasmolysis ex- 

 periments, the antagonistic action of various ions may be 

 satisfactorily explained by Loeb's suggestion, that they 

 mutually hinder penetration into the cells. It must be 

 remembered, in connection with objections which have been 

 raised to the method of plasmolysis, that the relative powers 

 of penetration and of antagonism of various salts have been 

 shown to be independent of the concentration within wide 

 limits. 



VARIATIONS IN THE PERMEABILITY OP THE LIVING CELL 

 INFLUENCE OF SALTS AND ANESTHETICS. 



It is held by some that permeability is a fixed property 

 of the cell, being only altered as the result of injury, in 

 which case the change is irreversible. 



The researches of Osterhout (1912, 2), however, afford 

 conclusive evidence that permeability may be increased 

 or decreased within certain limits, and that no injury 

 results from such alterations. For by means of sodium 

 solutions a decrease of over 10 per cent, was effected in 

 the electrical resistance of tissue, whereas the normal 

 value was recovered by restoration to sea-water. This 

 was repeated for fifteen days in succession without any 

 alteration in the normal resistance. Similarly, treatment 

 with salts of calcium or lanthanum resulted in a larger 

 resistance being met with, but this, too, was reversible and 

 capable of repetition for several days without evil effects. 



With regard to the action of anaesthetics very conflicting 

 views have been held. They were generally believed to 

 increase permeability, though some physiologists thought 

 the opposite to be the case. Undoubtedly the effect of 



