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Relation Between Death Temperature and Rate of Metabolism

respiration, species and temperatures


Column 7 of the table gives the temperatures found to be fatal to the different species on an exposure of 1 hour. When compared upon this basis the species studied fall into several groups; 2 of them succumb at 34.5° C.; another larger group finds the fatal temperature at 35° C., 2 others at 37° C., 2 at 37.5° C., while 1 species only could withstand temperatures up to 38.2° C. Although the last-mentioned species has the lowest respiration rate as well as the greatest power to withstand high temperature, there is no constant relationship between the death temperature and the respiration-rate when all the species are com pared. All of the species of the genus Gorgonia and the closely related Xiphigorgia, which have as a group the highest rate of respiration, are next to Briareum the most resistant to increased temperature. The two forms which are killed at the lowest temperature include Eunecia crassa, with next to the lowest rate of respiration, and Pseudoplexaura crassa, which stands eighth in the order of magnitude of respiration.

Taken all together these observations offer no support to the hypothesis of Winterstein (1905), but on the contrary indicate that some other factor is the controlling agency in the ability of a marine organism to withstand high temperatures.

The heat experiments were performed in an open jar containing 6 liters of water and at the end of any experiment the amount of oxygen contained in the water was more than sufficient to allow respiration to go on in a normal manner if no other factor than oxygen tension were concerned. The acidity of the water at the close of the heat experi ments was always greater than in respiration experiments carried on at 27.5° C. This may be only an expression of the abnormality of their metabolism at high temperatures, or have a causal relation to the death of the organism.