RELATION TO 0XVGI<:N. 



53 



sliould be disturbed as little as possible after inoculation, and especiall}' 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 

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



Fig. 47.* 



Fig. 48.t 



Fig. 49.t 



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 samjjle tube of this sort was filled with 



*FiG. 47. — Fermentation-tube with Bacillus tracheiphilus, 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, i. e., enough to render the fluid slightly alkaline to litmus. 



fFiG 48. — Fermentation-tube with Bacillus /rac/K^i/i/if/K.?^ showing inability of organism to grow 

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

 tonuni siccum 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. 



jFiG. 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. 



