On the Modification of Temperature Characteristics. I

The temperature characteristics for frequency of pulsation in isolated cloacal ends of Holothuria tubulosa are micro = 20,400 from 10 to 20 degrees , 8,000 from 20 to 30 degrees . The critical temperatures 10 degrees , 20 degrees , 30 degrees are related to thermal conditions in the environment. In sea water with doubled NaCl content micro = 8,000 from 10 to 30 degrees . This is consistent with the specific nature of the temperature characteristics. The primary effect of increased NaCl is to alter the temperature characteristic curve. At low temperatures the frequency is increased, at higher temperatures diminished. The effect upon frequency is thus of less significance. It is pointed out that such relationships must be taken into account in analyzing the action of reagents upon organisms.