425 
may allow, then, that the presence of such organisms in reasonable 
number would not render a milk harmful to man. Lux’s experi- 
ments have shown that with very ordinary care it is possible to 
obtain a milk containing on an average 1,400 bacteria per cubic 
centimeter, and it is obvious that with some trouble the number 
may be reduced. 
The work of Park,® 1901, Nicolle and Petit , b 1903, Conn and 
Esten, c 1904, Koning/ 1905, Harrison/ 1905, and others has shown 
that if milk be rapidly cooled to 11° C. (50° F.) or below, very little, 
if any, multiplication of micro-organisms takes place for some twelve 
hours. Therefore Park’s suggested average standard of not more 
than 12,000 bacteria per cubic centimeter in warm and 5,000 in cold 
weather for freshly drawn milk seems a generous standard and one 
which, with a little care, should be easily attained. 
It is necessary to note that ''separator milk” must not be judged 
by the same standard as fresh milk, for Severin and Budinoff/ 1905, 
and Severing 1905, have shown that even when every possible pre- 
caution is taken against contamination, the milk issuing from the 
separator always contains many more bacteria than it did before it 
passed into the separating chamber. Severin suggests that the 
mechanical movement completes the separation of bacteria which 
were only partially divided when they entered the machine. 
Moore h concludes from a large mass of data that freshly drawn 
fore milk contains a variable but generally enormous number of 
bacteria, but only a few species, the last milk containing as compared 
with the fore milk very few micro-organisms. 
Russell 1 found that the mixed milk of a herd that is kept with 
any reasonable degree of cleanliness, if examined immediately after 
a Park. Wm. H.: The great bacterial contamination of the milk of cities. Can it 
be lessened by the action of health authorities? Joum. Hyg., vol. 1, 1901. p. 391. 
b Nicolle, C., and Petit, P.: Etude experimentale sur la question du lait a Rouen. 
Rev. med. de Normandia, 1903. Rev. Bull, de Plnst. Pasteur, vol. 2, 1904. p. 552. 
c Conn. H. W., and Esten, W. M.: The effect of different temperatures in deter- 
mining the species of bacteria which grow in milk. Storrs Agric. Exper. Sta., 16th 
ann. rep., June 30, 1904. pp. 27-88. 
d Koning: Biologische und biochemische Studien iiber Milch. Milchwirtschaftl. 
Centblt., vol. 1, 1905; Rev., Cent. f. Bakt., 2 Abt., vol. 14, 1905. p. 424. 
e Harrison, F. C.: A comparative study of sixty-six varieties of gas-producing bac- 
teria found in milk. Cent. f. Bakt., 2 Abt., vol. 14, 1905, p. 359. 
/Severin, S., and Budinoff, L.: Ein Beitrag zur Bakteriologie der Milch. Cent. f. 
Bakt., 2 Abt., vol. 14, 1905, p. 463. 
0 Severin, S.: Vermindert die Zentrifugierung die Bakterienzahl in der Milch? 
Cent. f. Bakt., 2 Abt., vol. 14, 1905, p. 605. 
h Moore: U. S. Bur. Animal Indus., 1895-6. 
1 Russell, H. L. : Outlines of dairy bacteriology, 1896, p. 59 
