Doane,[122] working with _Bacillus Bulgaricus_ as a starter, found that these starters did not always overcome the undesirable fermentations. If a cheese-maker is having difficulty to develop the holes or "eyes," this may be overcome by making a starter[123] as follows from good cheese and whey or milk: Select a cheese which has the desirable "eyes" or holes and a good flavor. Grind up some of this and add about ¼ of a pound to one gallon of milk or whey. Hold this for twenty-four hours at a warm temperature (85° to 90° F.). Strain it into the vat of milk just before the rennet is added. +270. The making process.+--The milk is delivered twice a day without cooling. It usually reaches the factory at a temperature of 92° to 96° F. It is strained into the kettle, and starter and rennet added at the same temperature as received. (For method of adding rennet, see Chapter V.) Enough rennet should be used to give a coagulation ready for cutting in twenty to thirty minutes. The firmness of the curd is tested by inserting the index finger in an oblique position, then raising it slightly and with the thumb of the same hand starting the curd to break or crack. When the curd is coagulated ready for cutting, it will give a clear break over the finger. It is important to keep the temperature uniform while coagulation is in process, and this is best accomplished by the use of a little pan arrangement which fits into the top of the kettle. When this is full of water at 100° F., the temperature of the air above the milk will be about 90° F. When the curd is ready for cutting, a scoop may be used and the top layer carefully turned under to equalize the temperature more closely. _Cutting the curd._--In some cheese factories, knives resembling Cheddar cheese knives are employed to cut the curd. In other factories, a "Swiss harp" is used to break the curd. The curd is usually cut or broken into pieces about the size of kernels of corn. The practice of "breaking" curd instead of cutting it with sharp curd-knives produces excessive loss at times. Experimental study has shown that the loss of fat may be kept as low as 0.3 per cent if modern curd-knives are substituted for the breaking tool formerly used. Study of Swiss cheeses of all grades supports the opinion that the removal of a small part of fat from usual grades of factory milk produces a better quality of product than the use of rich whole milk. This may be accomplished through the escape of fat in the whey on account of breaking the curd and stirring it vigorously, or by skimming a part of the milk which is then curdled, cut and stirred under such conditions as to minimize the loss of fat.