60 STORRS AGRICULTURAL EXPERIMENT STATION. 
tables are studied; for it is seen that the difference is not a dif- 
ference of average simply, but a difference in practically every 
sample. ‘The milk aseptically drawn, and containing small 
numbers at the start in every case, showed a very much smaller 
number of bacteria at the end of 12 hours, 24, and 36 hours 
than the milk drawn in the ordinary way. Here again the 
difference may be due in part to the fact that the aseptic milk 
contained a larger proportion of bacteria capable of growing , 
only at high temperatures. 
3. The effect of aseptic milking upon the development of | 
acid in the milk was also noticeable. No increase in acid was — 
found in the samples 24 hours old, but in 36 hours the ordin-— 
ary milk showed an increase in acid from about .19 to .26, 
whereas the aseptic sample showed, even at 36 hours, no in- | 
crease in acidity. 
4. The time of curdling of the milk was similarly affected 
by the aseptic precautions. ‘The ordinary milk curdled on an 
average in 79 hours; the aseptic milk in 113 hours. 
5. Aseptic milking affects the percentage of lactic bacteria 
that is found in milk 36 hours old. In the non-aseptic samples 
there was an average of 86 per cent., and, leaving out one 
anomalous case, the 36-hour sample contained 100 per cent. of 
lactic bacteria. ‘The aseptic samples, on the other hand, varied 
widely. ‘There was an average of 51 per cent. at 36 hours, but 
this average, we notice from the table, is made up of numbers 
varying from I to98 per cent. The aseptic precautions clearly, 
then, have an influence in checking the development of the 
ordinary lactic bacteria. ‘This is a confirmation of the fact 
already noted in another place, that the milk freshly drawn 
from the cow does not contain the normal lactic bacteria. The 
aseptic milk, which excludes most of the external bacteria, 
therefore was likely to contain none or very few of these normal 
dairy forms at the outset. This explains readily enough the 
lower percentage of lactic organisms found at later hours in the 
aseptic milk. 
6. The increase of bacteria in the aseptic sample in 36 hours 
was about 200,000-fold, in the ordinary milk about 100,000- 
fold. Whether this difference has any significance is doubtful. 



