FEBRUARY 9, 1912] 
The gas ratio is further correlated in some 
cases with the fermentation of certain carbohy- 
drates. 
The group giving a ratio of 1:1.6 to 1: 2.0 
shows a distinctly greater ability to ferment sac- 
charose, raffinose and starch than the group giving 
the ratio 1: 1.1. It is probable that these tenta- 
tive groups are somewhat heterogeneous and that 
further refinement by the use of new test sub- 
stances will bring out sharper distinctions. 
The Bacteriology of Cheddar Cheese: E. G. Has- 
TINGS and ALIcE C. EVANS. 
Will appear soon in bulletin form jointly from 
the Dairy Division, Bureau of Animal Industry, 
U. S. Department of Agriculture, and the Wiscon- 
sin Experiment Station. 
Some Actions of Microorganisms upon the Con- 
stituents of Butter: CHARLES W. BROWN. 
For this work one lot of cream, divided into 
two parts—one part pasteurized at 160° to 170° F., 
the other not pasteurized—was churned and the 
butter placed in storage at —3°F. to + 3°F. 
Of the 88 different species of microorganisms, not 
including molds or the higher bacteria, isolated 
from this butter 57 are bacteria (cocci, bacilli or 
spirilla) and 31 are yeasts. It was noticed: 
1. That 24 of the bacteria and 15 of the yeasts 
will grow on 12 per cent. salt at 20°C. Four of 
these bacteria and six of these yeasts grow well on 
12 per cent. salt at 6° C. 
2. That the ratio of the number of species of 
liquefying bacteria to the number of non-liquefy- 
ing bacteria isolated from ordinary agar is the 
same as the liquefying to the non-liquefying iso- 
lated from 12 per cent. salt agar. 
3. That 12 per cent. of salt has a much more 
inhibitive action upon the species of liquefying 
yeasts than it does upon the non-liquefying. 
4, That the lactose in both the pasteurized and 
unpasteurized butter decreased from 0.315 per 
cent. and 0.325 per cent. to 0.285 per cent. to 
0.290 per cent., respectively, in 428 days. 
5. That 50 per cent. of the decrease in lactose 
took place within the first 10 days. 
6. That when the butter was taken from storage 
at the end of 428 days and placed at room tem- 
perature very little further decomposition of lac- 
tose occurred. 
7. That the soluble nitrogen recorded in per- 
centage of the total nitrogen in the butter in- 
ereased in 428 days from 6.25 per cent. and 7.69 
per cent. to 6.29 per cent. and 7.84 per cent. for 
the pasteurized and unpasteurized, respectively. 
SCIENCE 
231 
8. That the acidity of the pasteurized butter re- 
mained constant while that of the unpasteurized 
increased from 25.5° to 33.9° (Fuller’s scale). 
9. That when the growth upon synthetic agar 
was compared with the growth upon the same agar 
to which 1 per cent. butter fat—freed from im- 
purities by melting and decanting—was added, 9 
species of the bacteria showed a more luxuriant 
growth in the presence of fat, 11 were inhibited 
and 37 were indifferent; while 20 of the yeasts 
grew more luxuriant, 5 were inhibited and 6 in- 
different. 
A Bacteriological Study of the Milk Supply of 
Washington, D. C.: J. J. Kinyoun and L. V. 
DEITER. 
A series of bacteriological examinations of the 
milk supply of Washington, D. C., were continued 
over a period of 14 months beginning in Septem- 
ber, 1910, and ending on November 1, 1911. The 
objects of these examinations were to ascertain as 
near as was possible the actual conditions of the 
milk supply during this period so as to be able to 
formulate some means of its improvement. 
Samples of milk were examined in accordance 
with the rules and methods prescribed by the 
Laboratory Section of the American Public Health 
Association and in addition thereto special meth- 
ods were employed for the detection of the colon 
group. 
The result of this study was that the milk 
supply of Washington was on the whole very un- 
satisfactory and was capable of a great improve- 
ment. 
Nearly all the raw milk arriving in the city by 
rail had a very high bacterial content, the average 
for all samples for the 14 months was 9,300,000 
and in no instance was it below 1,000,000. 
55 per cent. of the samples contained both 
colon and streptococci. The close parallel be- 
tween these two groups is looked upon by the 
writers as a sure indication of dirty collection and 
imperfect handling. 
The examinations of the ‘‘pasteurized’’ milk 
as it is purveyed is far from satisfactory. This 
condition was due in a great measure to the im- 
perfect way in which the process was applied, or 
to the attempts of the dealer to pasteurize an old 
or a dirty milk in order to sell it. 
It has been clearly demonstrated by this study 
that a great amount of the milk as supplied is 
collected under unfavorable conditions, and is im- 
perfectly or carelessly handled. 
