RELATION TO OXYGEN. 



53 



should be disturbed as little as possible after inoculation, and especially all tiltings 

 or rough jarring should be avoided. They may be carried in a wooden rack (fig. 46). 

 All culture-media, whether inoculated or not, should be protected from light. 



Figs. 47, 48, 49 show fermentation-tubes in actual use. 



The pattern of fermentation-tube preferred by the writer is that slight modi- 

 fication of Einhorn's tube designed by Dr. Theobald Smith (see Wilder Quarter 

 Century Book). The tubes may be had from Emil Greiner, New York. Certain 



Fig. 47* 



Fig. 48.t 



Fig. 494 



forms of tubes should not be used. One of these, a short, thick tube with a wide 

 U, in use in some laboratories in this country, allows air to pass readily into the 

 closed end and is entirely worthless. A sample tube of this sort was filled with 



*Fic. 47. Fermentation-tube with Bacillus tracheifhilus, showing absence of gas and uniform 

 clouding in open and closed end in the presence of grape-sugar. The fluid consisted of water, 400; 

 Savory & Moore's peptone, 4; sodium chloride, i; c. p. grape-sugar, 2; saturated solution carbonate 

 of soda (20 C), 20 drops, '. e., enough to render the fluid slightly alkaline to litmus. 



tFiG 48. Fermentation-tube with Bacillus tracheiphilus, showing inability of organism to grow 

 anaerobically with glycerin as the carbon food. Fluid, distilled water with I per cent Witte's pep- 

 tonum iiccum and I per cent Schering's c. p. glycerin. Copious growth in open end and in outer 

 part of U ; none in the closed end. 



jFic. 49. Fermentation-tube of cane-sugar peptone water inoculated with a white, gas-forming 

 organism plated from a spot disease of sisal hemp. The total amount of gas produced and its rate 

 of evolution at 20 to 23 C. are indicated by marks on the closed end of the tube. 



