436 



M. H. JACOBS 



to substitute for I the numerical vale 1.0 and solve the equation 

 for p. In such cases (taking logio 2 = 0.3) 



logi 



P = 



07 

 tlo 



0.3 



The results of applying this method to a gradual and regular 

 rate of temperature increase in the case of starfish larvae are 

 shown in table 3. In the first column is given the rate at which 

 the temperature was raised, in the second the observed death 

 point, and in the third the point at which death ought theo- 

 retically to have occurred (i.e., the point at which the area 

 enclosed by the curve becomes unity) when the value of the 

 constant, Qi, was taken as equal to 2 (this value holding approxi- 

 mately for all of the starfish larvae studied). The value of lo, 

 which varies somewhat for different lots of larvae according to 

 age, etc., was determined especially for the animals used in these 

 experiments, and was found to be 0.05 at the temperature 

 (33°C.) chosen for comparison. 



It must be recognized, of course, that for the portion of the 

 curve between room temperature and 32°, no exact observations 

 are available, and it is uncertain to what extent the above equation 

 applies to it. But the area of this portion of the curve is in any 

 case so small as compared with that above 32° that the final 

 result would be little affected even if a different relation were 



TABLE 3 



Temperatures at which death of starfish larvae occurred afte- varying rates of tem- 

 perature increase from a starting point of approximately 20°C . 



