136 MARKET DAIRYING 
weeds of the garden correspond to the bad fermentations 
of cream. If the weeds get the start of the cultivated 
vegetables, the growth of the latter will be checked or 
suppressed. So with the bacterial fermentations of 
cream. When the lactic acid bacteria predominate, other 
fermentations will be checked or crowded out. The 
use of a liberal amount of starter nearly always insures 
a majority of good bacteria and the larger this majority 
the better the product. 
Classification of Starters. Starters are divided into 
two general classes, namely, natural starters and com- 
mercial starters. The former consist of naturally soured 
milk or skim-milk and are generally less satisfactory 
than starters prepared from commercial cultures. There 
are comparatively few natural starters used at the pres- 
ent time. Commercial starters are sent out in hermetic- 
ally sealed bottles and, in the majority of cases, may be 
obtained in either liquid or powder form. The bacteria 
will keep longest in the powder preparation, but will be 
found most active in the liquid provided the same is used 
immediately. 
NATURAL STARTERS. 
Sour Milk and Skim-milk. Natural starters are those 
obtained by allowing milk, skim-milk, or possibly cream, 
to sour in the ordinary way. 
The earlier methods of using natural starters consisted 
in selecting milk or skim-milk from the patrons who 
furnished the best milk at the creamery, and allowing this 
to sour by holding it over till the following day. While 
good milk could be selected in this way, the method of 
souring it was very unsatisfactory. On warm days the 
milk might oversour, while on cooler days it would be 
