118 SOME RECENT RESEARCHES IN PLANT PHYSIOLOGY 



For it is only in exceptional cases, when it has proceeded 

 but a very little way, that the process can be even partially 

 reversed. These facts all favour the view that the true 

 anaesthetic action is due to a decrease in permeability. 



Similar investigations by the electrical method have 

 demonstrated that sucrose, glucose, and glycerine, sub- 

 stances so frequently employed in plasmolytic researches, 

 all cause a marked, but reversible, increase in permeability. 



TABLE XXX. 



EFFECT- OF LIQUID AIR IN RENDERING PROTOPLASM 

 PERMEABLE. 



There can now be no doubt that Osterhout has shown 

 that the permeability of the plasmolytic membrane is 

 variable, and that it depends on the nature of the sub- 

 stances with which it is in contact. Thus the internal 

 surfaces, of the nuclei, vacuoles, and plastids, may have a 

 permeability which differs considerably from that of the 



