A STUDY OF RESPIRATION IN ALCYONARIA. 



By Lewis R. Gary. 



Although the respiration of many species of invertebrates has been 

 studied in considerable detail, the only references to that of Alcyonaria 

 which have come to the attention of the writer are those given by 

 Montuori (1913), who studied two species, Alcyorneuyn pallidum and 

 Gorgonia cavolinn. Two records only are given for each species, a 

 small and a larger specimen having been compared in each case. In 

 these experiments the total weight of the colony was taken as the basis 

 of comparison without taking into account the proportion of inert 

 skeletal material — the spicules in the first species and the spicules and 

 chitinous axis in the latter. 



Benedict (1915) has emphasized particularly the importance of the 

 proportion of active protoplasmic tissue as shown even in the com- 

 parison of individuals of different sexes of the same species. 



The observations herein recorded were made as part of a study of 

 the ecological factors determining the distribution of Alcj^onaria on 

 the coral reefs of southern Florida. The data from which the amount 

 of living tissue in the several species could be calculated were obtained 

 three years ago in connection with a study of the importance of the 

 alcj'-onaria as coral-forming organisms (Cary, 1915). A series of exper- 

 iments were also carried out on the same species to determine their 

 powers of resistance to increased temperature in order to discover 

 whether or not there is any direct relationship between the rate of 

 respkation and the temperature at which any species is killed ; in other 

 words, to determine whether the death of marine animals when sub- 

 jected to high temperatures is in reality the result of asphyxiation, 

 as Winterstein (1905) has maintained. 



EXPERIMENTAL. 



The respiration chambers consisted of museum jars, with clamped 

 tops fitting on rubber gaskets. The capacity of the several jars varied 

 from 960 c.c, to 1,250 c.c. as was determined by weighing each one 

 empty and again when filled with distilled water at a known temper- 

 ature. In all experiments with Alcyonaria the displacement of the 

 specimen was determined and subtracted from the capacity of the 

 jar. Frequently, when it was desired to make several determinations at 

 intervals on the same specimen a fragment of coral rock was allowed 

 to remain attached to the specimen in order to keep it upright during 



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