648 
marketed contain respectively 8 per cent. 12 per cent, 16 per cent. 20 
per cent, and 40 per cent of fat. 
PART III.— INFANT FEEDING. 
NUTRITIVE REQUIREMENTS OF INFANTS. 
It is obvious that any inquiry into the methods of infant feeding 
demands an intelligent comprehension of their nutritive requirements. 
Yet this phase of the question has been the object of scientific study 
only of recent years. Why this has been so, it is difficult to under- 
stand, seeing that we have long been possessed of very precise data 
as to the calorific value of the various articles composing the adult’s 
dietary and the amount of heat units required to maintain their 
nutrition under various circumstances. And yet, until the investi- 
gations of Heubner and his co-workers, our knowledge of the nutri- 
tive needs of infants has been mainly empirical and based merely on 
clinical observations, observations which I may add have been the 
source of serious error; 
The world is indebted to O. Heubner of Berlin, who was the first 
of a series of investigators, now rapidly increasing, for the discovery 
of facts which go a long way toward solving the difficult problem of 
infant feeding. Heubner,® appreciating that the principles underly- 
ing the feeding of infants, could only be worked out, as in the case of 
adults, from the logical basis of the number of calories per kilogram 
of body weight required by them for the purposes of growth and 
nutrition, undertook a series of exhaustive experiments with this end 
in view. 
Like most fundamental investigations, his line of procedure was 
quite simple, being merely to determine the daily amounts nursing- 
children took at the breast, each day for successive months, to tabulate 
the daily and weekly gains observed and finally, to determine by 
chemical analysis the composition, and from that the calorific energy 
of the milk that produced it. 
His results show that on the average, nursing infants, in order to 
thrive, require the following food value, or energy quotient as he 
calls it, per kilogram of body weight : First week in life, 60 calories * * 6 
per kilogram of body weight; first three months, 100 calories per 
kilogram of body weight ; second three months, 100 to 90 calories per 
kilogram of body weight ; third and fourth three months, 80 calories 
per kilogram of body weight. 
His results were confirmed by Feer, Nordheim, Beutner, Czerny, 
Keller, and others. He also found that an energy quotient of 70 was 
° O. Heubner, Die Energiebilanz des Siiuglings. Zeitschrift f. diatet. u. physik. 
Tlierapie, 1901, Yol. Y, p. 13. 
6 This term, as used in this paper, refers to large calories, or the amount of 
heat requisite to raise 1 kilogram of water 1° C. in temperature. 
