76 CULTURES OF BACTERIA. 
(dz) Dry, fix, stain, and mount as for ordinary 
preparations. 
Museum preparations of gelatin or agar tube or 
plate cultures may be made by exposing the 
cultures to formaldehyd vapor until the growth is 
killed, and then sealing the tubes or plates tightly 
with sealing-wax or paraffin. 
Fic. 47.—Bacterium tuberculosis: adhesive preparation 
from a fourteen-day blood-serum culture; x I0o (Frinkel 
and Pfeiffer). 
VI. CULTURES IN THE FERMENTATION-TUBE. 
This method is for the purpose of studying gas 
formation, and for the study of the aérobic or anaé- 
tobic properties of organisms. 
(a) Prepare fermentation-tubes with dextrose, lac- 
tose, or saccharos¢ bouillon. 
(4) Inoculate the tubes by floating a little of the 
