Mar. 12 , 1917 
Spore-Forming Bacteria of the Apiary 
401 
Bouieeon. —Most of the bouillon used was prepared from beef, and 
such bouillon is more satisfactory than that from meat extract, provided 
a good quality of fresh meat is available. Bouillon was also prepared 
from Liebig's meat extract, using 0.3 gm. of the extract per 1,000 c. c. 
of water, adding 1 per cent of Witte's peptonum siccum and 0.5 per cent 
of sodium chlorid. Bouillon prepared from meat extract should be used 
only when good fresh meat can not be secured. 
Sugar-free) bouieeon. —The small amount of muscle sugar present 
in bouillon made from meat is eliminated by inoculating with B. coli 
communis. Fermentation tubes of bouillon prepared from Liebig's meat 
extract, when inoculated with B. coli communis , failed to yield gas and 
increased acidity; hence, such bouillon may be used as a base for sugar 
media without being treated with this organism. Dunham's peptone 
solution is also used sometimes instead of sugar-free bouillon in growing 
cultures for the indol test and in preparing the various sugar media. 
Its use is quite satisfactory in the study of the reaction changes from day 
to day, but is not satisfactory for the observation of growth characteristics. 
Acid and neutrae bouieeon. —Plain bouillon is made neutral or 
acid to the desired degree by adding the proper quantity of N/i sodium 
hydroxid or N/i hydrochloric acid, as determined by titration. 
Agar. —One and one-fourth to one and one-half per cent of agar-agar 
in plain bouillon is used. The appearance on agar plates of the mem¬ 
bers of the group studied constitutes an important differential point; 
hence, this is a valuable medium. Owing to the absence of muscle sugar 
in the bouillon prepared from Liebig's extract, it was found desirable 
to add about o. 1 per cent of glucose to such agar medium. 
Potato seopes. —The potatoes are thoroughly washed and peeled by 
removing generously the outer portions, after which cylinders are re¬ 
moved by means of a cork borer and cut diagonally. The pieces are 
washed in several changes of water, tubed with a liberal quantity of 
water, and sterilized. It is advantageous to leave a liberal quantity of 
water in the tubes on inoculation, otherwise characteristic growth is not 
apt to occur. 
Serum. —This medium is prepared from both calf's blood and that of 
the horse by heating them over a period of several days in a serum 
inspissator after the usual described methods. 
Potato water. —A few of the strains were inoculated into potato 
juice prepared by adding an equal amount of water by weight to very 
small pieces of potato, boiling, straining, and filtering the mixture, and 
then distributing into test tubes. Little value is attributed to this 
medium alone, since the growth does not differ from that on slopes 
with a liberal quantity of water. 
Miek. —Owing to the difficulty of procuring separator milk, bottled 
milk, as purchased on the market, is used, first pipetting off the top 
cream, heating, setting aside overnight, again pipetting off any layer of 
