1! 



Pub. Puget Sound Biol. Sta. 



Vol. 2, No. 45 



(1904-5, 1915) has made many comparisons of the osmotic pressure of 

 the blood and body fluids of marine animals with that of the water in 

 which they live, and with but few exceptions finds that the two are the 

 same, — that there is no excess of inner concentration over that outside 

 the organism. He succeeded in adapting animals to water of greater and 

 of lower salinity, and in most cases the body fluids decreased or increased 

 their concentration until it was the same as that of their environment. 



4. OSMOTIC PRESSURE OF SEA WATER 



It is interesting to note that the osmotic pressure of Puget Sound 

 water is lower than that of waters from other regions of the earth in so 

 far as reports have been made, except in a very few cases. From the 

 measurements made at Friday Harbor it averaged 19.2 atmospheres, but 

 of course it undergoes diurnal and seasonal variation. At the Golden 

 Gate, San Francisco, Garry (1915) reports that on ]\Iarch 17, 1904 

 A=1.47° at high tide, 1.385° at low tide; on September 23, A=1.80°; 

 so that from March to September the osmotic pressure varied from 16.6 

 atmospheres to 21.64 atmospheres. The water of the Atlantic coast 

 Avhere A=2.0° C. has a considerably higher salt content as does the water 

 also at Pacific Grove, California (A^1.9°). The former's pressure would 

 be 24.04, the latter's 22.84 atmospheres. I have found no figures for any 

 other locality on the Pacific Ocean. The greatest depression reported 

 is at Naples where A^2.29°, corresponding to an osmotic pressure of 

 27.51 atmospheres. 



A more detailed comparison of the water at Friday Harbor with that 

 of Woods Hole is interesting. In the following tabulations, the specific 

 gravity and salt content of the water at Friday Harbor are obtained from 

 tile titration of the chlorine* content by means of Petterson's (1894) ta- 

 ble; and the chlorine and total salt content of the Woods Hole water are 

 obtained from Garry's (1915) density reading by using Petterson's table. 



Table 2. Tabulated comparison of the salinity of the sea tcater at Friday 

 Harbor and Woods Hole 



A , in degrees centigrade 



Osmotic pressure in atmosptieres- 



CI content in grams per liter 



Salt content 



Specific gravity 



Friday Harbor 



1.597 

 19.204 

 16.9 



2.95% 

 1.022 



Woods Hole 



l.Sl 

 21.76 

 17.5 

 3.1% 

 1.024 



* The titration for chlorides gave the same CI content as that reported by Shelf ord (1915) for 

 Friday Harbor water. 



