432 



M. H. JACOBS 



the amount of injury inflicted in unit time at any one tempera- 

 ture to that inflicted in the same time at any other temperature 

 is, for a certain range, in the forms studied, governed by a simple 

 mathematical law, it is possible by making observations at a 

 few selected temperatures, and thus determining the necessary 

 constants, to calculate the theoretical effect of a continuous 

 change of temperature at any desired rate. The details of the 

 method will be made clearer in the following sections where the 

 actual experiments are discussed. 



4. EXPERIMENTS ON STARFISH LARVAE 



Since the results obtained with starfish larvae are simpler than 

 those with Paramecium, they may be considered first. In 

 table 1 are given the lengths of exposure found to cause death 

 when the animals were suddenly subjected by method 1 to the 

 temperatures in question. The fatal exposure in each case is 



TABLE 1 



Times required to kill approximately one-half of the individuals of starfish larvae 

 when suddenly subjected to various temperatures 



