the Second Series should be used.

_Why is it necessary to make the food so weak at first?_

Because the infant's stomach is intended to digest breast milk, not
cow's milk; but if we begin with a very weak cow's milk the stomach
can be gradually trained to digest it. If we began with a strong milk
the digestion might be seriously upset.

_How rapidly can the food be increased in strength from Formula I to
II, from II to III, etc.?_

No absolute rule can be given. Usually we begin with I on the second
day; II on the fourth day; III at one week or ten days; but after that
make the increase more slowly. A large infant with a strong digestion
will bear a rather rapid increase and may be able to take V by the
time it is three or four weeks old. A child with a feeble digestion
must go much slower and may not reach V before it is three or four
months old.

It is important with all children that the increase in the food be
made very gradually. It may be best with many infants to increase the
milk by only half an ounce in twenty ounces of food, instead of one
ounce at a time as indicated in the tables. Thus from 3 ounces, the
increase would be to 3½ ounces; from 4 ounces to 4½ ounces, etc. At
least two or three days should be allowed between each increase in the
strength of the food.

_What general rule can be given for increasing the food?_