Propagation of Starters 201 
On the other hand, a considerable number of fac- 
tories in this country have secured an increased flavor 
and quality in their product from ripening their 
cream with the aid of either Hansen’s ferment or B. 41. 
The use of culture starters both for the ripening of 
cream and the ripening of milk for cheese-making has 
now become almost universal, particularly in factories, 
and practice in the culture of such starters is a neces- 
sary part of the training of all successful butter and 
cheese makers (see Appendix A). Skill in the culture 
of starters depends very largely in keeping everything 
surrounding them bacteriologically clean, so that, no 
matter how skilfully directions for the propagation of 
starters may be written, very few will learn except 
by actual experience the necessity for bacteriological 
cleanliness. 
The only reason for a starter becoming impure or 
going “off flavor” is that it becomes contaminated 
from some outside source, and this comes from lack of 
eare in handling it or allowing it to come in contact 
with some person or thing that is not sterile or “bac- 
teriologically clean;” hence, in tasting or otherwise 
examining a starter from which a culture is afterward 
to be made, a portion should always be removed from 
the starter with a clean spoon or other suitable article, | 
and such portion must be discarded after the examina- 
tion has been made. The practice of dipping the fin- 
ger into a starter and then tasting or smelling it is 
the best possible means of destroying it. 
Where a starter is properly and carefully propa- 
gated, it is not only possible to keep it for a long time, 
