tO 
2 STORRS AGRICULTURAL EXPERIMENT STATION, 
a larger amount of pasteurized cream. But practical difficul- 
ties rendered this method unsatisfactory, and it was found 
necessary to devise a method of furnishing the culture to the 
butter-maker in large quantities direct from the laboratory, 
thus saving him one step in the process. After some experi- 
ments a device was adopted by which the culture was furnished 
in the form of a moist pellet, something after the fashion of a 
compressed yeast cake. ‘The manipulation of producing these 
cultures in large quantities is, however, proving extremely 
difficult. Bacteria are so abundant in the air and in all liquids 
that it has been found a matter of excessive difficulty to culti- 
vate Bacillus No. 41 in such way as to keep it pure and uncon- 
taminated by the hosts of mischievous germs that come from 
various sources. It has been found necessary to use definite 
temperatures and special media for growth of the Bacillus, and 
even after it has grown it is very difficult to determine whether 
it is pure or whether it has become contaminated. This latter 
circumstance has proved very troublesome, and it has taken 
six months to learn positively how. to recognize contaminated 
cultures quickly. For this reason it has been impossible to 
furnish the culture to the extent that it would have been 
desirable. Moreover, even at present the methods adopted are 
not wholly satisfactory. The difficulty of contamination is so 
very great that it requires the most careful and constant study 
with the microscope to determine whether the cultures sent to 
the butter-makers are pure cultures of Bacillus No. 41 or are 
mixed with others. Furthermore, in the form in which the 
cultures are sent it was found that, during the hot weather, 
moulds would very commonly develop on the pellet, and the 
presence of the moulds has proved injurious to the action of 
the culture. The methods of producing these cultures in large 
quantities are being constantly improved, and at the present 
time nearly all of the difficulties have been mastered. It is 
felt that no further trouble is to be anticipated from the con- 
tamination of the cultures by the growth of moulds or other 
organisms therein. The methods, however, are not yet per- 
fected and will not at the present time be described. 
The use of this new form has proved a great aid in correct- 
ing errors in handling the culture. The greatest source of 
trouble has been in building up the culture from a small 
