Effects of Temperature on Tropical Marine Animals. 



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Record No. 2. A Cassiopea xamachana cooled from 29.5 to 16.8 C. and then 



warmed to 30.9 C. 



the square of the departure of the temperature from its optimum of 33. 

 Thus a change in temperature above or below the optimum appears to reduce 

 the rate of pulsation in proportion to the square of the change. For 

 example, if cooling 1 C. produces a loss of rate of i per minute, a cooling 

 of 2 from the optimum will produce a loss of 4, and for 3** the loss will 



be about 9, etc. 



Thus if X be the departure of temperature from the optimum of 33 (for 

 example at 30 or at 36, x = 3), and if y be the loss in rate (for example, if 

 the rate has declined from 34 to 30, 3' = 4) then in cooling y = 0.122x2, 

 and in heating y = 0.926x2. 



It seems that the loss of rate in heating is nearly 8 times as rapid as in 

 cooling. Moreover, when the medusa has lost all movement through being 

 heated, its muscles are relaxed and recovery rarely occurs, even if the medusa 

 be then cooled to a normal temperature. If, however, the medusa be cooled 

 to a standstill, the muscles still exhibit a decided tonus, some shrinkage 

 occurs, and the slime congeals into a gelatinous mass. 



The falling-off in rate that is observed when the medusa is either cooled 

 or heated from its optimum temperature appears not to be a simple chemical 

 reaction, for it is more rapid than can be represented by the equation 



