METABOLIC PROCESSES 



THE PLANT. 



263 



fermentation by means of Kiihne's fermentation vessels* (see Fig. 

 !M). The tube of the apparatus is completely filled with Pasteur's 

 food solution, the bulb being left empty. We now pass a pellet 

 of yeast into the fluid. In consequence of the evolution of Carbon 

 dioxide which at once commences, the food solution is driven out 

 of the tube into the bulb. If we then introduce a fragment of 



FIG. 95. Apparatus for demonstrating 

 the production of Carbon dioxide in fer- 

 mentation. 



FIG. 96. Kiihne's fermenta- 

 tion vessel. 



caustic potash into the apparatus, the fluid returns into the tube 

 since the Carbon dioxide is absorbed. 



If a tall glass cylinder is half filled with Pasteur's food solution, 

 und, after addition of pressed yeast, is closed not quite air-tight, 

 we can soon detect the Carbon dioxide formed by simply intro- 

 ducing into the cylinder a burning taper. The flame is extin- 

 guished. 1 



1 I have stated my views regarding normal and intramolecular respiration in 

 my Lehrluch d. Pjianzenphysiologic, Breslau, 1883. See also Detmer, Prings- 

 heim's Jahrbiicher /. witsenschl. Botanik, Bk. 12, and Berichte d. Deutscheii 

 botan. Gesellschaft, Bd. 10, p. 433. 



Any glass-blower will make them. 



