OXYGEN CONSUMPTION IN ACIDS. 289 



LITERATURE. 



Surprisingly enough, very few investigations have been carried 

 out on the effect of increased acidity on the respiratory meta- 

 bolism of organisms. A rather careful search through the 

 iterature has revealed only the following researches. 



Among plants, only the lower forms have been investigated. 

 Brooks ('21, '22) measured the carbon dioxide production of 

 Bacillus butyricus, B. subtilis, and B. tuberculosis at various 

 hydrogen ion concentrations. The bacteria were tested in dex- 

 trose solutions made in distilled water and the desired acidity 

 was obtained with sulphuric acid. The rate of carbon 'dioxide 

 production was at the maximum at pH 7.0 for B. butyricus, at 

 pH 6.8 for B. subtilis, and was decreased at all acidities greater 

 than these. In the case of B. tuberculosis, however, the carbon 

 dioxide production was constant at all acidities between pH 7.4 

 and 4.4 and was decreased only at acidities greater than 4.4. 

 Gustafson ('20) studied the effect of altered acidity on the 

 respiration of the mold Penicillium chrysogenum. Variations in 

 acidity between pH 8.0 and pH 4.0 were without effect upon the 

 rate of carbon dioxide production. In acidities ranging from 

 pH 4.0 to 2.65, the carbon dioxide output first rose and then 

 fell; below 1.95 an irreversible decrease in the output was 

 observed. The oxygen consumption was measured at pH 2.0 

 and was found to be markedly increased over the normal, thus 

 agreeing with the initial carbon dioxide production at this 

 particular acidity. In Gustafson's experiments, the mold was 

 tested in dextrose solutions in distilled water and sulphuric and 

 phosphoric acids were employed to increase the acidity. 



Among animals, a few researches are available on eggs, tissues, 

 and intact animals. Loeb and Wasteneys ('n) found that the 

 oxygen consumption of sea-urchin eggs is slightly decreased in 

 sea-water acidified to pH 6.0 to 4.0, and considerably decreased 

 at or below pH 4.0. Thunberg ('09, '10) has carried out a large 

 number of experiments on the action of acids on the rate of 

 oxygen consumption and carbon dioxide production of surviving 

 frog's muscle. The tests were performed in salt solution. Thun- 

 berg unfortunately did not determine the pH of his solutions 

 this procedure was not customary at that time but gives the 



