A good deal can be said for the use of skimmed or separated milk instead of whole milk. Cream as a rule contains far more bacteria than the rest of the milk, and we therefore start from a surer foundation when it is removed; besides, the mechanical separator, now so largely used, removes slime and other impurities from the milk, and these also are hotbeds of bacteria. Soured milk may be taken at any time, the first thing in the morning, before or after meals, or the last thing at night. The quantity will vary with the individual, but from half a pint to a pint is a fair amount for daily use. If one wishes to have the maximum effect it is necessary for the time being to curtail the use of butcher's meat and substitute fish, yolk of eggs, and other similar foods; not much alcohol should be taken, and smoking might be reduced to a minimum. Those who cannot take even skimmed milk may use whey in which to cultivate the bacillus; it is not desirable to employ the whey which has been separated by the use of rennet, as in cheese- or junket-making. A better article is obtained by adding a very small quantity of pure hydrochloric acid to milk which has been boiled, and then filtering through a sieve, which retains the curd while the liquid whey passes through; a pinch of soda is added to neutralise the excess of acid, and, after boiling, the liquid should turn red litmus paper blue; it is then ready for the addition of the culture and incubation in the same manner as with milk. A solution of malt—the extract dissolved in hot water is convenient—may also be used instead of milk, and strongly malted bread or biscuits are excellent to take with the soured milk or cultures in other mediums, to supply food for the bacillus in the form of malt sugar. Other sugars, cane or grape, are also very useful, and may be taken in the form of fruit juices, syrups, confections, jams, sweet puddings, etc.