412 MILK AND MILK PRODUCTS 
There are occasionally a few variations desirable from these rules, 
but it may be well to state that the details have been pretty carefully 
and thoroughly worked over and compared, and it is seldom that short 
cuts can be made if correct results are desired. The time and speed of 
centrifuging are placed as low as possible for accurate work. When 
there is $ ¢.c. or more of sediment, it is necessary to use more of the 
methylene blue for staining, as there will be too great a number of leu- 
cocytes to make a satisfactory count in the counting ¢hamber, it is better 
to add water until there are 2 ¢.c., or sometimes even more in the sedi- 
mentation tube. 
This method of counting, while long in explaining is in reality short 
and simple in application. Moreover, it is based on accurate measure- 
ments in every detail, and the results are correspondingly reliable. 
(From Report of Committees of the Laboratory Section, American 
Public Health Assn. Am. J. Pub. Hyg., 6 (1910), 
PaTHOGENIC Bacteria IN MILK 
Bacillus tuberculosis. The tubercle bacillus is recognized as one 
of the most important pathogens in relation to the milk question. While 
it may gain entrance from a tubercular person handling the milk, it is 
generally admitted that a tubercular cow is usually the source. Human 
tuberculosis is probably transmitted directly from human to human 
but may be transmitted by bovines, especially those with udder infec- 
tions. Griffith (1918) reports the discharge of virulent tubercle bacilli 
in the milk of a heifer which had been vaccinated when four days old 
with human tubercle bacilli. Other experiments by Smit (1908), 
Coquot (1908), Hessler (1909), indicate that there is slight possibility 
of the tubercle bacilli being discharged into milk unless there are open 
lesions. Smit found few tubercle bacilli in milk from tuberculous 
animals with sound udders but where open tuberculosis existed the 
bacilli could gain entrance to the milk from all channels which com- 
municate with the exterior. This subject has been well summed up by 
Schroeder (1907). 
Delepine’s Method for Determining Tubercle Bacilli in Milk (from 
savage, 1914). Collect two tubes of milk containing 40 c.c. and cen- 
trifugalize for fifteen minutes at 3000 r.p.m. Decant or draw off the 
cream and milk by means of a pipette leaving about 2 c.c. of milk and 
residue in each tube. Examine microscopically and inject into guinea 
pigs. 
