COMPARATIVE STUDIES ON RESPIRATION. 



V. The Effect of Ether on the Production of Carbon 

 Dioxide by Animals. 



By MARIAN IRWIN. 



(From the Laboratory of Plant Physiology, Harvard University, Cambridge.) 



(Received for publication, September 6, 1918.) 



The purpose of this investigation is to make a comparison of the 

 CO2 output of animals with that of plants under the influence of a 

 t5^ical anesthetic such as ether. One obstacle to such a comparative 

 study is found in the fact that the movements of animals are more or 

 less inhibited by anesthetics; such inhibition diminishes the CO2 

 output even when it is not due to anesthetics. Hence it is difficult 

 to say how the CO2 output would be affected by anesthetics if this com- 

 plication were absent. This difliculty is largely avoided in my studies 

 on frog eggs and Fundulus embryos, while in the investigations on 

 tadpoles and on aquatic insects it is partly obviated by the method of 

 experimentation. 



No attempt has been made to compare the results with those ob- 

 tained on animals by other workers, such as those of Tashiro,^ 

 because the methods were so different as to render a comparison 

 difficult. 



Method. 



The method used in determining the output of CO2 is the one de- 

 scribed by Haas. 2 The standard buffer solutions were made with 

 mixtures of phosphates. To 10 cc. of the solution, three drops of 0.01 

 per cent solution of phenolsulfonephthalein were added; in all the 

 experiments sufficient NaOH was added to bring the pH value to 

 8.0. As the concentration of NaOH was the same in all cases the 



^ Tashiro, S., A chemical sign of life, Chicago, 1917, 

 2 Haas, A. R. C, Science, 1916, xliv, 105. 



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