THE OSMOTIC PRESSURE OF SEA WATER AND 

 OF THE BLOOD OF MARINE ANIMALS. 



INCLUDING SOME OBSERVATIONS ON THE PERMEABILITY OF 



ANIMAL MEMBRANES. 1 



WALTER E. CARREY. 



Experimental work on the relation of salts and other substances 

 in solution to the life processes of marine animals requires an 

 accurate knowledge of the osmotic pressure of both the sea water 

 and the body fluids of the animals. This knowledge should be 

 supplemented by definite information relative to the permeability 

 of the membranes of the animals under investigation. Thus far 

 this field has been neglected by American investigators. It has 

 been assumed that local conditions are similar to those existing 

 along the European sea board. Owing to the character of the 

 work in our Marine Laboratories it seemed advisable to make 

 some observations which would place our knowledge of local 

 conditions on a firmer basis. 



METHOD. 



Until recently our knowledge of sea water and animal fluids 

 has been based solely on quantitative chemical analyses. F. 

 Bottazzi 1 at Naples in 1897 calculated the osmotic pressure from 

 the depression of the freezing point. This method has since 

 been used by several investigators working in the same field 

 (Rodier, Quinton, Fredericq) and was adopted as most con- 

 venient for our purpose. Employing the Beckmann apparatus 

 the freezing point is determined. For aqueous solutions a freez- 

 ing point below that of distilled water signifies the presence of 

 some substance in solution which is exerting an osmotic pres- 

 sure. This pressure calculated for o C. is equal to about twelve 



1 These investigations were made at the Marine Biological Laboratory, Woods 

 Holl, Mass. They were reported to the Biological Seminar, August 12, 1904. 10 

 Investigations conducted on the Pacific Coast will be reported later as they are still 

 in progress. 



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