ae BULLETIN 717, U. S. DEPARTMENT OF AGRICULTURE. 
The many studies which have been made to determine the actual 
importance for dietary purposes of the proteins supplied by meats, 
eggs, and milk show quite conclusively that these proteins are of 
high biologic value. Unfortunately the supply of these food mate- 
rials is becoming constantly less adequate to meet the needs of the 
very rapidly increasing population of this country. Furthermore, 
these foods are relatively expensive, and consequently can not be 
eaten as freely as formerly by those of small incomes. As a result of 
these conditions, students of nutrition have given considerable 
attention to the possibility of replacing animal proteins with vege- 
table proteins, and as a consequence the demand for vegetable foods 
which supply proteins that are of value for human food is steadily 
increasing. The cereals which contain relatively small amounts of 
protein are already so extensively used that as a group they now 
supply nearly one-half of the total protein of the average American 
diet. While practically all of the common vegetable foods contain 
protein, the amount present in foods of vegetable origin is small except 
in the case of the legumes, which may be classed as protein-rich food. 
Accordingly it appears that a more extensive use of legumes as a 
source of protein is to be desired. Those legumes most commonly used 
in this country are the well-known navy beans, red kidney, and lima 
beans, the garden pea, frijoles, pinto beans, and several varieties of 
cowpeas. Many studies have been made of the nutritive value and 
possible uses of these legumes, and several investigators have con- 
ducted experiments to determine their digestibility. 
INVESTIGATIONS OF DIGESTIBILITY OF COMMON LEGUMES. 
The digestibility of hulled peas cooked thoroughly until soft and 
passed through a sieve was determined by Rubner,! who found that 
the protein was 72 per cent digested. In a second experiment in 
which the subject ate 600 orate of peas per day the digestibility was 
found to be 83 per cent. 
Malfatti ? determined the digestibility of the protein supplied by a 
porridge made of split peas and found it to be 86 per cent digested. 
Richter * reported that in an experiment in which the subject con- 
sumed 600 grams of purée of pea the protein was 90 per cent 
digested. 
Snyder‘ conducted three experiments to determine the digesti- 
bility of pea protein. and served a porridge (containing 82 per cent 
of water) made from dried peas. The porridge was eaten in conjunc- 
tion with a basal ration consisting of rice, milk, and sugar; one- 
third of the protein of the diet was supplied by the peas. He found 
that the average digestibility of the pea protein was 80 per cent. 
1Ztschr. Biol., 16(1880), No. 1, pp. 119-128, 3 Arch. Hyg., 46 (1903), No. 3, pp. 264-273. 
2 Jahresber, Tier-Chem., 15 (1885), p, 412, 4 Minnesota Sta. Bul. 92 (1905), pp. 267-270. 
