a BULLETIN 642, U. S. DEPARTMENT OF AGRICULTURE. 
square feet of light for each cow. Five hundred cubic feet of air 
space was provided for each cow. An untrained milker, wearing 
ordinary work clothes and giving no special attention to the cleanli- 
ness of his hands, was employed to milk and take care of the cows. 
During the work the cows were alternated from time to time in 
order to equalize any unusual results due to the individual animal. 
For example, in working with the small-top and open pails two cows 
were milked first into the open pail and a few days later were milked 
into the small-top pail. | 
In all the work the milk was poured unstrained into cans in the 
barn. The small-top pail used in the experiments was the type with 
Fic. 1.—Experimental barn used in this investigation. 
a hood or cover on an ordinary pail, as shown in figure 2. Utensils 
were sterilized by being placed in a sterilizer, steamed for 30 minutes, 
and afterwards allowed to remain there until used. When the uten- 
sils were not sterilized they were merely washed clean and inverted 
in the milk house. Covers were not placed on the cans, and the ~ 
utensils were left in that position until time to milk. 
Sterile utensils in the strict sense of the term means their absolute 
freedom from living organisms. When the statement is made that 
utensils were sterilized it means that they were free from all bacteria 
which are destroyed by flowing steam at 100° C. (212° F.). There 
are, of course, a few spores which are resistant to flowing steam and 
which can be destroyed only by steam of high temperature under 
pressure. 
Oe a a 
