DIGESTIBILITY OF CKREAL BREAKFAST FOODS. 183 
Duration.—In general, the longer the digestion experiment 
the more reliable the results, because errors such as might 
oceur from failure to obtain complete separation of the feces 
for the digestion period would thus be proportionally smaller. 
It was desired to have each of these experiments continue 
not less than three days, and preferably four days. Five of 
the experiments continued part or all of the fourth day, and 
the other four terminated with the end of the third day, as 
explained beyond. 
Diet.—The diet in these experiments consisted of the break- 
fast food with milk and cream anda little sugar. No restriction 
was placed upon the amount of any food material to be eaten, 
each subject choosing what seemed to him to be sufficient to 
satisfy his needs. Some of the subjects, however, endeavored 
to have the cereal portion, at least, of the different meals some- 
what uniform in amount. 
The diet was purposely made as simple as possible consistent 
with palatability, in order that the availability of the cereal 
portion alone might be computed, as hereafter explained. 
- Theoretically, an ideal diet for investigations of this nature 
would consist of only the material studied; but experiments 
with men on a single food material are not practicable, for 
several reasons. In the first place, the very monotony of the 
diet might prove an objection, because for subjects accustomed 
to a varied diet a ration of but one food material commonly 
becomes decidedly unpalatable after a few meals, so that it 
cannot be eaten for as many days as desired for satisfactory 
experiment. In the second place, the availability of a given 
food material when eaten alone appears to be not the same as 
when eaten with other materials. In experiments with bread 
and milk, for instance, when the ration contained both mate- 
rials the availability was greater than when either material was 
eaten alone. In fact the nutrients of the simple diet of bread 
and milk were about as completely available as those of a more 
_ varied diet. 
In view of these facts, in order to increase both the palata- 
bility and the availability of the ration over that of one con- 
sisting of the cereal food alone, it was deemed best to include 
the other foods mentioned above with the breakfast food. 


