Respiration, Aeration, and Fermentation 303 



Pour this into a 1-liter Erlenmeyer flask and add 2 grams of 

 pressed yeast. Fit the flask with a cork through which passes 

 the short arm of a piece of glass tubing bent so that the long 

 arm may reach over through the cork of a wash bottle containing 

 baryta water. Do not connect with the baryta water, however, 

 until there is time for the air in the flask to have been driven 

 out by the gas which is being produced. (How may this be 

 determined, approximately?) Describe the result. 



When the fermentation is practically complete, or after one 

 week, the flask containing the fermented solution may be con- 

 nected with a condenser and distilled. At a temperature of from 

 80-85 C. redistill, and when a few cc. have been caught note the 

 odor ; then pour into a test-tube, add a crystal of iodine, heat 

 gently to 60 C., and maintain at this temperature while adding 

 a strong solution of caustic soda until the iodine dissolves. A 

 yellow precipitate of iodoform is indicative of the presence of 

 alcohol. 



REFERENCES 



BARNES, C. R. The Theory of Respiration. Bot. Gaz. 39 : 



81-98, 1905. 

 BLACKMAX, F. F. Optima and Limiting Factors. Ann. of Bot. 



19 : 281-295, 2 figs., 1905. 



BUCHNER. Ber. d. deut. chem. Gesellsch. 30:117-124, 1896. 

 FUHRMANN, F. Vorlesungen iiber Bakterienenzyme. 136 pp., 



9 figs., 1907. 

 KLOCKER, A. Fermentation Organisms. (Transl. by G. E. 



Allan and J. H. Millar.) 392 pp. 

 KOSTYTSCHEW, S. Ueber die norm. u. die anaerob. Atmung bei 



Abwesenheit von Zucker. Jahrb. f . wiss. Bot. 40:563-592, 



1904. [See also Ber. d. d. hot. Ges. 24 : 436-441. 

 PEIRCE, G. J. A New Respiration Colorimeter. Bot. Gaz. 



46 : 193-202. 

 PURIEWITZ. Physiolog. Unters. iiber Pflanzenatmung. Jahrb. 



f. wiss. Bot, 35 : 573-610, 1900. 



