COMPARATIVE STUDIES ON RESPIRATION. 



III. The Effect of Ether on the Respiration and Growth of 



Bacillus subtilis. 



By matilda MOLDENHAUER BROOKS. 



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



(Received for publication, September 6, 1918.) 



Although so much stress is laid on the physiological reactions of 

 bacteria in their identification and classification, little investigation 

 (except to distinguish aerobic from anaerobic forms) has been devoted 

 to the fundamental process of respiration in these organisms. In 

 order to throw some light on the nature of this process and to com- 

 pare the results with those obtained with other plants and with ani- 

 mals, a series of studies upon the respiration of bacteria has been un- 

 dertaken. The present paper describes the results of some experi- 

 ments on the effects of ether. 



The organism selected for experimentation was Bacillus sublilis, 

 isolated from water and inoculated upon agar-agar daily during the 

 month previous to experimentation, so that a pedigreed culture was 

 at hand. Several other organisms were tried; namely, Bacillus 

 mycoides, Staphylococcus pyogenes albus. Staphylococcus citreus, Bacillus 

 typhosus; but Bacilhis subtilis was preferred because it was easier to 

 handle. Bacteria were incubated for 16 to 18 hours at 37°C. and were 

 then washed into a test-tube with a few cc. of tap water containing 

 indicator. A thick emulsion was made by repeatedly drawing the 

 Hquid into, and ejecting it from a pipette which was drawn out to a 

 very fine point. 



The respiration of the bacteria was tested in boiled tap water. The 

 boiling rendered the water alkaline by driving off the CO2. To each 

 2 cc. of solution was added one drop of a 0.01 per cent aqueous solu- 

 tion of phenolsulfonephthalein. The color of the solution was com- 

 pared with the colors of a set of standard buffer solutions, made ac- 

 cording to Sorensen's directions with KH2PO4 and Na2HP04, hav- 



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