A photomicrograph of curd just after curdling has taken place. Note the few lactic acid bacteria embedded in the curd.] =Starters in cheese making.= The starters used in cheese making, are identical with those employed in butter making and the same precautions should be observed in their propagation. It is important that the starters should not be such as to form a hard curd that cannot be mixed uniformly with the milk, since the curd particles would appear as white specks in the cheese. The starter should be added to the milk through a hair sieve, and well mixed with the milk, so as to distribute the bacteria uniformly. Amounts varying from 0.5 to 2 per cent are used. In butter making, it is essential that the bacteria of the starter be able to form not only acid, but sufficient flavor-forming substances to impart to the butter a desirable flavor. In cheese making it is not probable that this latter characteristic is of any particular importance. [Illustration: Fig. 36.--Bacteria in Cheese. A photomicrograph of curd at the time the salt is added. The lactic acid bacteria have increased materially in numbers.] It is desirable that the process of cheese making shall conform as closely as possible to that which experience has shown to give the best results. The rate at which acid is developed in the curd and the rapidity with which the whey is expelled therefrom should bear a certain ratio to each other. If the milk has too high a degree of acidity, _i.e._, is overripe, the acidity developed in the curd will be too high before the curd is sufficiently firm; with a very sweet milk, the reverse may be true. It is desirable for the cheesemaker to obtain as good an idea as possible of the condition of the milk with reference to its bacterial content, since this will determine the rate at which acid will be formed in the curd. If the milk is too sweet, _i.e._, too low in acid-forming bacteria, a starter should be added. The only methods by which this information can be obtained by the maker is by determining the acidity by the usual method or better by the use of the rennet test by which is ascertained the time required for a given amount of rennet to curdle a definite quantity of milk at a standard temperature. The varying factor in the test will be the acidity of the milk. Very slight differences influence profoundly the time of curdling. If, working under standard conditions, it is found that the time of curdling of one sample is 10 seconds and of another sample, 20 seconds, it is proof that the acidity of the first is higher than that of the second, that its bacterial content is greater and that acidity will develop in the curd more rapidly. The first may need a small amount of starter, the second a larger quantity. Working with milk from the same source, the maker, from his experience, will know how much starter should be added to milk that has given a certain result with the rennet test in order that the acid shall be developed in the