262 PHYSIOLOGY OF NUTRITION. 



instead of mercury for the sealing fluid. Both tubes are sup- 

 plied with plant material, neither of them being provided with 

 potash solution. We employ 5 gr. of pea seeds or 5 gr. of wheat 

 grains, and 5 gr. of hemp grains. The two lots of material are 

 separately weighed, and after being soaked, the starchy material 

 is placed in one of the tubes of the apparatus, the fatty material 

 in the other. The apparatus being kept in a place in which the 

 variations of temperature are not considerable, it will be found 

 that the level of the water does not change much in the course 

 of one to two days in the tube containing the starchy seeds. In 

 the other tube, however, the water rises considerably. The fatty 

 grains of course, like the starchy ones, undergo normal respira- 

 tion ; at the same time, however, the former exhibit that form of 

 respiration which I have termed vinculatory respiration (Vincula- 

 tionsatlimung'). The essential feature of this consists in absorption 

 of Oxygen without corresponding formation of Carbon dioxide, 

 and the bound Oxygen is employed in converting the fat into 

 substances richer in Oxygen (carbohydrates). 



Lastly, we completely fill the upper part of one of our tubes 

 with flowers (Rosa or Dahlia, etc.), or with seedlings of Vicia 

 Faba. We suck the water up to a considerable height, close the 

 stop-cock, and let the apparatus stand. The material at first 

 undergoes normal respiration. Soon, however, the Oxygen of the 

 air in the tube is consumed, and now, even with somewhat falling 

 temperature, the column of water begins to sink. Owing to 

 intramolecular or internal respiration in the Oxygen-free space 

 the plant material produces Carbon dioxide. The volume of gas 

 in the apparatus is thereby increased, and the water is depressed 

 in the tube. 



To prove the production of Carbon dioxide (respiration) in 

 fermentation, we put together the apparatus depicted in Fig. 95. 

 We place in the flask A 200 c.c. of Pasteur's food solution (see 18), 

 and add to it about 5 gr. of pressed yeast. Fermentation soon 

 sets in. The liberated Carbon dioxide can be detected by means 

 of the clear lime water or baryta water contained in the flask 13. 

 Fermentation and copious development of Carbon dioxide do not 

 take place when the fluid to which the yeast is added differs in 

 composition from Pasteur's food solution in containing no sugar, 

 and in having Ammonium nitrate in place of the Ammonium 

 tartrate. 



We can also readily prove the formation of Carbon dioxide in 



