OSMOTIC PRESSURE IN ANIMALS AND PLANTS 577 



accumulation of large quantities of sugar would induce dis- 

 turbances. It is therefore hardly accidental that it is in the 

 group of organisms possessing the power of assimilating carbon 

 dioxide that a more or less inextensible bounding membrane 

 was developed. 



Finally, since water is a necessity for all protoplasmic life, 

 and since between protoplasm and the external medium, the 

 internal vacuole boundaries, and the numerous compartments 

 and plastids in the cytoplasm one meets with all sorts and 

 degrees of semi-permeable membranes, it becomes apparent that 

 questions in which osmotic pressure effects have to be considered 

 abound in most branches of physiology. 



In conclusion the writer wishes to state that the present 

 paper was written under circumstances which cut him off from 

 all reference to journals, reprints, or notes of any kind. While 

 tolerably sure of the accuracy of the figures and names of 

 authors given in the text, he is forced to acknowledge with regret 

 his inability to recall the names of some of the workers whose 

 researches he has mentioned. 

 Egypt, September 30, 1916. 



38 



