190 Papers from the Department of Marine Biology. 



metabolism occurred as frequently when the specimen had all its polyps 

 completely withdrawn as when they were in full expansion. 



Although the area of tissue exposed to the water had no constant 

 effect on the rate of respiration, there was a striking relationship 

 between the proportion of surface to weight of the several species and 

 the rapidity of their respiration. As shown in column 6 of table 1, 



those species which have the greatest surface for a unit of weight 

 / cm 2 \ 



( ) have bv far the highest metabolism. The areas used in these 



Vgms./ 



calculations were determined accurately for each specimen by measur- 

 ing the length and the diameter of each branch of a colony and treat- 

 ing them as cylinders or cones according to their shape. Under the 

 conditions necessarily imposed while making the measurements, the 

 colonies were always in a state of complete contraction, so that, when 

 the specimens were in full expansion, the values of S/W would be from 

 1.25 to 3.25 times greater than those recorded in the table. 



RELATION BETWEEN DEATH TEMPERATURE AND RATE OF METABOLISM. 



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 Eunccia 

 crassa, with next to the lowest rate of respiration, and Pseudoplexaura 

 f-nissa, 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. 



