INVESTIGATIONS OF ACID ORGANISMS OF MILK. etre 
2. When milk ts drawn from the cows in such a manner as to 
exclude from wt dirt and dust from the atr, the stable, and the cow, 
such milk may contain none of the organisms capable of producing 
a normal souring of milk. In the large herd of 70 cows expert- 
mented upon this was seen to be the case with each cow. 
3. Lhe three normal species of lactic bacteria are a secondary 
contamination of the milk from some external source. 
g. In the dairy experimented upon, while all three species of 
lactic bacteria were present in the air, the B. acidt lactict TI. 
appear to be present tn the smallest numbers, although apparently 
so abundant that all samples of milk tf exposed for a short time 
well become infected with tt. 
5. None of the three species of lactic bacteria was found in the 
udder of the cows examined, which ts in accordance with the re- 
sults of others who have examined the udders of cows. 
6. The udders of the cows examined contained a single species 
of micro-organism, apparently identical with that found by Ward 
in the udder, and by Conn found very commonly present in mulk. 
7. The tnvasion of the milk by the udder bacteria is of no great 
importance so far as concerns the keeping quality of milk. Out 
of three hundred tests made of fore-milk drawn directly from the 
udder into sterile vials, only about 2 per cent. contained the normal 
acid bacteria, and these were all contaminations from the outside. 
