286 



PHYSIOLOGY OF NUTRITION. 



second or third day active fermentation. The evolution of gas 

 (C 2 and H) resulting from the spontaneous appearance of the 

 butyric organism is so energetic, as I have observed, that the 

 corks are forcibly expelled, and the fluids at once acquire the 

 characteristic smell of Butyric acid. We will now demonstrate 

 the anaerobic character of Clostridium butyricum, and for that 

 purpose put together the apparatus represented in Fig. 105. 



The flask d of about 500 c.c. capacity is about two- thirds filled 

 with food solution of the composition indicated. We plug the 

 mouth of the flask with cotton wool, and sterilise the solution by 

 boiling for about half an hour. After cooling, we remove the 

 cotton wool, quickly infect the contents of the flask with a few 

 drops of a fluid in which the butyric fermentation is already 

 proceeding, and at once close the flask with a very well-fitting, 

 two-holed rubber stopper. The glass tubes R', R", R'", bent as 



indicated in the figure, are 

 sterilised before the ap- 

 paratus is put together. 

 The longer limb of the 

 tube R'" opens below the 

 mercury in the bottle e. 

 R' and R" are connected 

 within the basin c by means 

 of the short piece of rubber 

 tubing, k. The bottle l> 

 contains a solution of Potas- 

 sium permanganate. We 

 now prepare Hydrogen by 

 the action of Arsenic-free 

 Zinc on Hydrochloric acid 

 (the water used to dilute 



KL 



. 



so as to free it as com- 

 pletely as possible from air), and let it enter the apparatus 

 at b, after passing through a wash bottle containing potash solu- 

 tion. This wash bottle and the Kipp's apparatus are not repre- 

 sented in the figure (but see Fig. 97). We lead Hydrogen through 

 the apparatus for about two hours, so as to displace all the Oxy- 

 gen, then pour mercury into the dish c and remove the connection 

 tubing &, so that the tube R" now opens under mercury. The 

 apparatus is put in a thermostat at 35 C. In the course of a few 



