Max. 25,1914 
Streptococci in Milk 
497 
rapidity and after three days there was no question that the cultures 
were able to utilize glycerin. Those represented by the curve Z>, on 
the other hand, produce only a very slight increase in acidity, which even 
at the end of 14 days is only slightly above 1 per cent normal. 
Between these two is a third group in which there is a slow but dis¬ 
tinct increase in acidity. At seven days the acidity is above 1 per cent 
normal. While an error may be introduced in some cases by drawing 
the line between fermentation and no fermentation of glycerin at 1 per 
cent normal, it is believed that in these results this error will be slight. 
These results illustrate the value of the exact results obtained by titra¬ 
tion which we have always used in preference to the simpler and more 
rapid way of determining the change of reaction with litmus in solution 
in the broth or with litmus papers. 
We also consider it a decided advantage to allow sufficient time for 
the completion of the fermentation, thus securing an end point rather 
than some intermediate and varying determination. Seven days are 
not sufficient for the completion of the glycerin fermentation, but it is 
undoubtedly ample for other test substances which we have used. 
Table I .—Progressive fermentation of dextrose and glycerin . 
Dextrose. 
ec . 
0.15 
0.19 
0.31 
0. 34 
0.44 
0. 55 
o- 58 
O. 91 
0. 53 
0. 96 
0. 78 
1. 21 
• 25 
• 2 3 
■ 80 
1. 67 
I. 31 
3. 65 
2. 73 
4. 96 
4. 85 
4. 96 
5.43 
eh. 
. 22 
.46 
•35 
i -57 
I- 54 
2- 40 
2.38 
06 
4. 61 
3*74 
4.68 
• IS 
• 14 
•37 
•37 
*96 
.86 
.28 
• 63 
1. 83 
.92 
•33 
i-13 
et. 
* 05 
• 59 
.82 
• 95 
I. 09 
1.30 
X* 49 
2. l6 
1. 73 
2. 18 
2. 30 
2. 63 
ev. 
•is 
.09 
•34 
• 17 
.00 
.40 
•45 
.66 
1. 03 
.96 
• 70 
1.18 
hw ... 
. 20 
. 11 
.67 
•95 
I. 07 
1-35 
I. 67 
1.38 
2. 08 
2. 71 
a- 45 
3-15 
nr . T , f . TT . 
• 15 
. 09 
• 14 
. 00 
. 00 
• 25 
• °3 
• 02 
• 3 1 
• 43 
. 76 
. 21 
jiy „ , T , . . 
. 20 
. 29 
• 04 
. 00 
* °5 
. 00 
. 01 
. OO 
. 21 
.00 
. II 
. 09 
• 02 
• 07 
. 09 
• 05 
. 02 
. 11 
.48 
.46 
• 03 
om. 
•is 
.00 
.09 
. II 
.09 
.06 
.00 
. 21 
• 13 
•19 
.00 
.00 
Pi. 
• 05 
.09 
. 22 
• 32 
.24 
•36 
•31 
• 71 
•53 
• 76 
.66 
•78 
THE CORRELATION OF PHYSIOLOGICAL CHARACTERS 
The complete results of the tests made on this collection of cultures are 
presented in Table II. The reduction of neutral red and the curdling 
of milk are given in the table, but are not used in the correlations. 
Adonite and dulcite are necessarily excluded, since these cultures almost 
without exception fail to ferment these two substances. 
