On Changes in the Sea and Their Relation to Organisms. 



237 



water and kept in an automatic burette with soda-lime tubes, and stand- 

 ardized with pure iodine. The starch solution was allowed to settle 

 and only the clear upper portion used. When dextrins appeared in it 

 a fresh solution was prepared. 



Although pH determinations and CO2 calculations were made in all 

 experiments, it was found that the oxygen absorbed could be deter- 

 mined much more accurately than the CO2 given out, and the CO2 

 determinations are not listed \vith the experiments, but are collected 

 together in the form of respiratory quotients. The respiratoiy quo- 

 tients were 0.7, 0.74, 0.76, 0.84, 0.85, 0.86, 0.88, 0.9, 0.91, 0.92, 0.97, 

 0.99, 1, .1.02, 1.03, 1.1, 1.15, 1.2. It was impossible to tell whether 

 the variation is due entirely to errors in the CO2 determinations or 

 whether the respiratory quotient varied. It is improbable, however, 

 that respiratory quotients of 1.2 existed for even short periods of time, 

 and these at least may be considered due to technical errors. Accord- 

 ing to Mayer (1914), Cassiopea lives on animal food exclusively and does 

 not absorb carbohydrates from its symbiotic algae, since it starves as 

 rapidly in the light as in the dark. It may, however, get some carbo- 

 hydrates from its animal food, or from glycoproteins during starvation. 

 In this connection it may be of interest to note that Cassiopea secretes 

 a mucin-like substance. Since the error in estimating CO2 production 

 may be 30 per cent in half-hour experiments with small cassiopeas, it 

 is convenient to assume that the respiratory quotient is constant and 

 is about 0.95, which is also the average found by Vernon for the hardier 

 species of jelly-fish, on which he made most of his determinations. 



The oxygen consumption is about doubled when the temperature is 

 raised from 20° to 30°, and from results on other animals is probably 

 an exponential function of the difference in temperature. Harvey 

 (see Mayer, 1917) found the velocity of the nerve-impulse in Cassiopea 

 to be a linear function of the temperature and to increase about 64 per 

 cent on raising the temperature from 23° to 33°. I found the activity of 

 the gangUa (rhopalia) in inducing pulsations of the umbrella to be about 

 doubled with rise from 20° to 30° in temperature. The data are given 

 in table 12. 



Table 12. Table 13. 



These experiments show the necessity of accurate temperature con- 

 trol, and in all of the other experiments in this paper the temperature 



