“STAB” CULTURES. 61 
(a) Does the bouillon become uniformly clouded, 
or only at the surface or bottom ? 
(4) Does a pellicle form on the surface or a de- 
posit at the bottom ? 
Fic. 36—Method of holding tubes during inoculation. 
(c) Is the color, odor, or reaction of the bouillon 
changed ? 
Il. GELATIN OR AGAR CULTURES. 
1. “Stab”? Cultures.! 
(1) Sterilize a straight platinum needle and touch 
it to the culture to be studied ; hold the gelatin- or 
agar-tube upside down, remove the cotton plug, 
and stab the needle carefully up through the cen- 
ter of the medium nearly to the bottom of the 
1“Stab” cultures are usually made in gelatin-tubes ; 
“stroke” cultures, on agar-tubes. 
