214 
Journal of Agricultural Research 
Vol. II, No. 3 
citric acid or lactose or protein, as the medium was practically free from 
fat. These organisms did not produce formic acid. As they are present 
at times in very large numbers in cheese, they, no doubt, produce much 
of the volatile fatty acids which arise during the ripening process. 
(2) One of the strains of Streptococcus b was found to produce com¬ 
paratively large quantities of alcohols and esters—bodies which con¬ 
tribute in a large degree to the flavor of cheese. 
(3) A dilute solution of acetic acid and alcohol formed esters by mere 
contact, without bacterial action. In cheese, however, the dilution is 
probably too great for this manner of ester formation. 
(4) Lactic acid was generally not formed by the coccus groups. 
(5) The representatives of the Bacterium casei group examined gave 
results differing from those obtained from the coccus forms. They pro¬ 
duced no formic acid, but did form some propionic and much acetic acid. 
(6) These organisms produced a large quantity of lactic acid, both 
active and racemic, and decomposed the citric acid of the media. 
(7) Cheese made from chloroformed fresh milk did not yield any 
volatile fatty acids, showing that inherent milk enzyms are not capable 
of producing these bodies in any appreciable quantity. 
(8) Representatives of both the coccus and Bacterium casei groups 
were able to produce ammonia from milk. 
(9) Whey and fresh curds contained active lactic acid. Cheese 1 day 
old contained a mixture of active and racemic lactic acids. 
(10) The cause of the disappearance of active lactic acid and the 
appearance of racemic acid may be due to enzymic action, combined' 
with the action of those bacteria which can produce both kinds of acid. 
(11) Some representatives of the Bacterium casei group produced 
levo lactic acid and others dextro lactic acid from milk. A mixture of 
these two varieties produced racemic lactic acid. A mixture of B. lactis 
acidi and a levo-producing member of the B. casei group gave racemic 
and active lactic acid. The active acid was probably the result of the 
longer continued activity of B. casei. 
(12) Racemic lactic acid found in curing cheese may therefore be pro* 
duced in a small degree by enzym action, but more probably by the 
combined action of Bacterium lactis acidi and the organisms of the 
B . casei group. 
LITERATURE CITED 
Babcock, S. M., and Russnu,, H. L. 
1897. Unorganized ferments of milk: a new factor in the ripening of cheese. In 
Wis. Agr. Exp. Sta. 14th Ann. Rpt. [i8g6]li8g7 t p. 161-193, hg* I 4~i5* 
-RussKUv, H. L., Vivian, A., and Hastings, E. G. 
1899. The action of proteolytic ferments on milk with special reference to galac- 
tase, the cheese-ripening enzyme. In Wis. Agr. Exp. Sta. 16th Ann. 
Rpt. [i8g8]li8gg t p. I 57 “i 74 > 2 pi. 
