
QUALITATIVE ANALYSIS OF MARKET MILK. 71 
in milk. Their presence in large numbers probably always 
indicates excessive filth; and we always regard with suspicion 
samples of milk containing numerous liquefiers. ‘The reasons 
for this suspicion will not be given at this point, beyond the 
general fact that liquefiers do not come from the milk ducts, 
nor are they likely to be abundant in milk pails. Consequently 
their presence means external contamination from manure or 
other dirt. 
In the experiments given below it was not always feasible to 
separate Groups V. and VI., and in some tables all liquefiers 
are given in one column. In such experiments it will be un- 
derstood that most of the liquefiers were slow growers. 
The next three groups consist of a single species each. None 
of them is apparently of much significance, and none of them 
has any effect on milk. Descriptions of the organisms will be 
published later. 
Group VIII. This is number 222 of our list, and is recog- 
nized from its producing a pale, thin colony upon litmus gela- 
tin. ‘The colony is slightly yellowish, grows under the surface, 
and is transparent. It proves to be difficult to cultivate and 
has no action on milk. It is found on nearly all samples of 
nilk, and sometimes in large numbers. It disappears as the 
milk becomes older. 
Group IX. ‘This is number 227 of our list, recognized by 
producing a ved-brown, opaque colony. 
Group X. This is number 228 of our list, recognized from 
its halo colony. ‘This has a dense center surrounded by a clear 
ring, growing below the surface. It proves to be a very slow 
liquefying colony, growing slowly. 7 
Group XI. Miscellaneous. In every sample of milk there 
is quite sure to be a small number of species of bacteria pecu-. 
liar to the sample but not found in other samples. Such species 
are usually easy to distinguish from the more common species. 
In some samples a single such species is found; in others four 
or five. ‘They are always few in numbers, usually less than 1 
per cent. Occasionally, however, one of these species may 
‘constitute 10 per cent. of the bacteria in a sample of fresh 
milk, indicating of course that there was in this case some 
