232 



Papers from the Department of Marine Biology. 



in CO2 tension and the latter might be considered constant. If there 

 were sufficient exchange between sea and air the CO2 tension of the 

 sea would be practically constant. In table 11, the sea-water ex- 

 amined by Dr. Mayer on the trip from San Francisco to Hawaii (if 

 we except the first station, where the water was polluted from land 

 drainage and came in an insensitive region of the thymolsulfon- 

 phthalein tubes) had an almost uniform CO2 tension, although the tem- 

 perature rose 6.2°, thus necessitating in total CO2 a fall of 1.3 c.c. per 

 liter and rise in pH of 0.08. This may not, however, have been entirely 

 due to exchange with the air in situ, but partly to the remote history of 



Table 11. 



a ll^'OO™ a. m. b 5'^00™ p. m. c .5''00'" a. m. 



d e^-oo- 



Y). m. 



7h30D 



the water. Palitzsch has shown that the pH of the open sea decreases 

 as the depth increases. It is well known that temperature decreases 

 as the depth increases, and the two factors would have antagonistic 

 effects on the CO2 tension and tend to keep it constant. The reason 

 for this stratification of the water may be that each stratum of water 

 reached a certain temperature and CO2 tension while at the surface, 

 and the temperature effect on the density caused the superposition of 

 the strata. After being buried out of reach of surface currents, the 

 temperature and total CO2 change very slowly and hence the CO2 



