OXYGEN CONSUMPTION IN ACIDS. 2QI 



abolition of oxygen consumption. Hydrochloric acid was less 

 effective than either of the two organic acids, producing only 

 50 per cent, depression at pH 3.0. 



There is a dearth of experiments on entire animals. Jewell 

 ('20) tested the carbon dioxide output of frog tadpoles in distilled 

 water acidified with HC1. The output was decreased to 92 per 

 cent, of the normal at pH 7.0, to 84 per cent, at pH 5.4, to 53 

 per cent, at 3.8, and to 37 per cent, at 3.2. Powers ('23) studied 

 the effect of carbon dioxide tension on the oxygen consumption 

 of the herring. He found the maximum oxygen consumption at 

 pH 7.6 to 7.8; alterations in the carbon dioxide tension, and 

 hence pH, either above or below this value, lead to a decrease, 

 rather slight, however, in the amount of oxygen consumed by the 

 fish. Powers ('22) is of the opinion that the ability of fish to 

 utilize oxygen depends to some extent on the pH of the water in 

 which they are living. 



In addition to such direct measurements of the effect of 

 increased acidity of the medium on respiratory exchange there is 

 available a considerable number of researches on the action of 

 acids on processes in which respiratory metabolism is undoubtedly 

 of great importance. Acidification of the medium has a general 

 retarding or depressing effect on such processes. I can refer 

 here only briefly to this literature. It is a well known fact, 

 attested by many researches, that acidification of the medium 

 retards the cleavage and development of the egg and produces 

 abnormal types of larvae (cf. Loeb, '98, Moore, Roaf, and Whitley, 

 '05, Child, '16, Medes, '17, and Smith and Clowes, '24, for 

 echinoderm eggs; Child, '25, for hydroids; Child, '17, for 

 annelids; Loeb, '98, and Hall, quoted by Shelford, '23, for teleost 

 eggs; and Hall, '24, and Bellamy, '19 and '22, on amphibian 

 development). The retarding effect of acids on regeneration 

 was noted by Jewell ('20). Acidification of the medium consti- 

 tutes a general method for altering and controlling polarities 

 (cf. Child, '23, and Rustia, '25). 



For a general summary of the role of acids in the behavior 



and life of aquatic organisms the excellent paper of Shelford 



('23) should be consulted. I am unable however to agree with 



Shelford that hydrogen ion concentration is of greater importance 



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