
78 STORRS AGRICULTURAL EXPERIMENT STATION. 
contained in all cases small per cents. of acid organisms. There 
are no striking exceptions to this rule in the samples given, 
although in experiment No. 4, showing a total number of 
14,500, there was 27.8 per cent. of acid organisms. ‘This is the 
only exception we have found to the rule that small total num- 
bers of bacteria mean small percentages of lactic organisms. 
From these results we draw the following conclusions: 
1. In our market milk the presence of a large percentage of 
acid organisms indicates that the milk is not fresh or has been 
kept under too warm conditions. 
2. If the milk contains a large total number of bacteria, the 
inference is that the great majority of these will be the harm- 
less and even useful lactic organisms. ‘This inference, how- 
“ever, is not always strictly accurate and could never be made 
with certainty without an actual qualitative test. | 
3. The next conclusion from our table is that when the 
number of bacteria is large, the number of varieties is small. 
This has been brought out in nearly every experiment, al- 
though again with no absolute regularity. Large numbers of 
bacteria always indicate a considerable percentage of lactic 
organisms, and the lactic organisms have a tendency to check 
the development of the other species of bacteria present, if not 
to actually destroy them. Hence, the older the milk, the less 
significant are the miscellaneous bacteria present. The con- 
verse of this proposition is usually, though not always, true; 
namely, that samples of milk containing small total numbers 
of bacteria contain a large number of varieties. This conclu- 
sion, as would be expected, cannot always’be relied upon, 
because some samples of milk may be obtained under such 
favorable conditions that the total number of bacteria and also 
the number of varieties are both small; but for a miscellaneous lot 
of milk samples this conclusion holds true. It must be pointed 
out that this conclusion is to be explained in a measure by the 
fact that the plates which were made of milk containing small 
numbers of bacteria had fewer individual colonies, and under 
these circumstances the differentiation of species is much more 
easy and accurate. It isa simpler matter to obtain the varie- 
ties of bacteria from samples of milk that contain small total 
numbers than from samples containing large total numbers. 

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