46 STORRS AGRICULTURAL EXPERIMENT STATION. 
heat it to 70° for five or six days in succession, and this 
process is so long and tedious that it was found to be practi- 
cally impossible under the conditions of the experiment. More- 
over, as the experiments continued, it became evident that the 
expectation that pasteurization so far destroyed bacteria as to 
render the experiments successful, was plainly realized. ‘Tests. 
were frequently made by comparing the pasteurized cream with- 
out inoculation, with pasteurized cream after inoculation, both 
lots being ripened for the same length of time at the same 
temperature. In all such experiments it was found that the 
uninoculated pasteurized cream was practically unripened at the 
end of the experiment, while the inoculated cream showed a very 
marked ripening, due to the bacteria inoculated. This was true 
only when moderate temperatures were used. Ata temperature 
of 35°C.(95°F.) the pasteurized cream became over-ripened. More- 
over, it was found that the experiments in general were uniform 
in their results. The same species of bacteria inoculated into 
the pasteurized cream gave, in all cases, under similar condi- 
tions, the same results. This, of course, would not have been 
expected had the few bacteria which chanced to be left in the 
sterilized cream had any marked effect. As will be seen later 
some irregularities were probably due to this unavoidable error. 
The control experiments which were occasionally performed in 
this way, gave us evidence enough that the method adopted, 
while not rigidly exact, was sufficiently exact for proper conclu- 
sions to be drawn as to the effect of special species. In one 
experiment, cream was inoculated with No. 27, was then 
pasteurized and inoculated with No. 18 and ripened. The 
resulting cream and butter were such as is produced by No. 18 
and no trace of No. 27 was seen. Moreover, it must be recog- 
nized that if artificial inoculation of cream ever becomes possible 
in butter making, it will probably never be possible for butter 
makers absolutely to sterilize their cream. The high tempera- 
ture required for this, rendering the butter worthless because of 
its boiled milk taste. Pasteurizing cream at 70°C. (158°F.) may 
be a practical possibility, though this may be questioned, and for 
this reason, in addition to those above given, this method of 
pasteurization was regarded in our experiments as preferable to 
any attempt at thorough sterilization of the cream. The chance 
of error, however, made it necessary to repeat experiments 
many times until uniformity was obtained. 

