i6 



Papers from the Marine Biological Laboratory at Tortugas. 



y = ac', but in all these experiments the equation y = bx^ fits the observed 

 facts fairly well, but this formula is merely tentative and should not be 

 taken as being more than an empirical attempt to express the law. If this 

 be the law, however, it would mean that the decline in rate varies as the 

 square of the degree of heating or cooling above or below the optimum, and 

 it leads one to suspect either that an inhibiting enzyme is formed in a 

 constantly accelerated ratio or a stimulating one is destroyed in the same 

 manner. This is, however, a mere suggestion, for the observations are too 

 few to establish it as a law. 



Experiments upon Cassiopea frondosa and Aurellia aurita at Tortugas 

 appear to lend some support to the results attained from a study of C. 

 xamachana. 



Thus table 3 shows the average rates of four medusae of Cassiopea 

 frondosa at Tortugas, Florida, cooled from 28.5° to 12.5° C, and figure 5 gives 

 a graphic representation of the results. It is evident that the rate declines 

 somewhat more slowly than if it followed the equation y = 0.0507X-. 



Table 3. 



13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 

 Degrees Centigrade 

 Fig. 5, illustrating Table 3. 



Upon being heated, Cassiopea frondosa begins to lose in rate at 32.45° 

 and all movement ceases at 38.3° C. Unfortunately, I did not make enough 

 observations to determine the curve of the decline, but if it be a parabola 

 its equation must be 3' = i.o^x^, and thus the decline in rate upon heating 

 above the optimum is about 20 times as rapid as the decline on cooling 

 below the optimum. 



Table 4 and figure 6 show the decline in rate of an Aurellia aurita from 

 Tortugas, Florida, cooled from 28.8° to 11.8° C. 



