36 



Papers from the Department of Marine Biology. 



By means of the conversion table (fig. 6) it is possible to determine the 

 CO2 tension of sea-water from the temperature and Pg as read by means 

 of the standard tubes and colorimeter described on pages 44-46. The 



6 7 8 9 1 

 X 10-9 X lO-s 



2 3 4 5 



H ion concentration 



7 8 910 



xlO" 



Fig. 6. — Conversion ta))le for finding the CO2 tension of sea-water from the Ph and the tempera- 

 ture. On the ordinate is measured the logarithm of the CO2 tension in ten-thousandths of an 

 atmosphere. On the abscissa is measured the Ph, with a scale below for converting it into the 

 normality of H ions. The four curves are for 30°, 20°, 10°, and 0°, the last of which has been 

 extrapolated. The crosses mark the determinations of Henderson and Cohn by the colori- 

 metric method at 20°. 



CO2 tension is of first importance in the respiration of marine organisms. 

 The rate of elimination of CO2 by animals and its absorption by plants 

 in the sunlight is directly proportional to the difference in CO2 tension 

 just outside and inside of the respiratory surfaces. Life in the sea is 



