14 
BULLETIN 148, U. S. DEPARTMENT OF AGRICULTURE. 
contact with the air after sterilizing. A can or receptacle which 
works very satisfactorily was devised by one of the authors (see text 
fig. 1). This starter-can consists of two tanks (5) and (11) con- 
nected by a block-tin collar (7) — brass can not be used, as it prevents 
growth of the culture. In this collar is fitted a tinned plug (8) , fas- 
tened to a tinned-brass pipe (6). A brass collar (1) large enough to 
let the block-tin plug- 
pass through is fast- 
ened at the top of the 
upper tank. Into this 
brass collar is fitted 
a brass plug (2), 
through which passes 
the tinned-brass pipe 
(6). Both the pipe 
and plug are threaded 
to permit the raising 
and lowering of the 
block-tin plug (8) be- 
tween the two tanks 
without raising the 
brass plug in the 
top tank. When both 
plugs are in place 
there should be an 
opening in the pipe 
at the point (4) to 
permit the air to pass 
from the lower tank 
(11) to the upper 
tank (5) when the 
whey is passing from 
the upper tank to the 
lower tank. The end 
of the brass pipe (6) 
extending above the 
upper tank should be plugged with cotton to prevent any outside con- 
tamination when the starter is drawn from the lower tank. The open- 
ing (3) in the top of the upper tank for filling is plugged with a cork 
into which is fitted a thermometer. The pipe. (12) for draining off the 
starter is placed about one-half inch from the bottom of the lower 
tank. This always leaves enough starter for reinoculation. The 
lower can is insulated with a zinc jacket filled with ground cork (9). 
-// 
<-/z 
~/0 
Fig. 1. — A mother-starter can for carrying pure cultures. 
Although it was designed especially to prevent cultures 
of Bacillus bulgaricus from yeast contamination in mak- 
ing Swiss cheese, it can be used for all whey cultures. 
