143 
Flour No. 11 contains 2 forms. 
a (1) Same as No. 1 a (1). 
a(2) Same as No. 3a (J). 
Flour No. 12 contains 3 forms. 
a(l) Same as No.7 b (@). 
b@) Same as No. 4 b (2). 
c(1) Same as No. 2 a(3). 
No.| No. of Forms. Bac. Per Gram. |Moulds Per Gram.|} Grade of Flour. 
1 3 4090 2272 High. 
2 3 2727 2727 High. 
3 4 | 14545 1363 Medium. 
4 6-1 yeast. 4545 909 High. 
5 2 9090 909 Medium. 
6 ] 2727 000 High. 
7 4 15909 DID Medium. 
8 3 222727 000 Poor. 
9 2 4545 4090 High. 
10 1 254545 909 Poor. 
11 2 6363 0000 Medium. 
12 3 18136 909 Poor. 
This work was done under the direction of Miss Katherine E. Golden. 
THE NuMBER OF MIcrOo-ORGANISMS IN AIR, WATER AND MILK As DETER- 
MINED BY THEIR GROWTH Upon DIFFERENT MEDIA. 
By A. W. Brirrine. 
While conducting a series of experiments to determine the number of 
bacteria and moulds in milk, some variations in number were found when 
the tests were made upon different culture media. This led to an experi- 
ment to determine the number of micro-organisms present in air, water 
and milk, using agar agar, glycerine agar, beef gelatine, and wort gelatine. 
The results of the test were somewhat of a surprise. The agar agar, 
glycerine agar and beef gelatine were neutral, while the work gelatine 
was slightly acid, but the degree of acidity not determined. Ten exposures 
were made with each media, using petri dishes and kept as close together 
as possible. The conditions were evidently as nearly alike as it is pos- 
sible to obtain. 
