DIGESTIBILITY OF RAW STARCHES AND CARBOHYDRATES. 7 
The coefficient of digestibility of the raw starch was 100 per cent 
for both subjects, and this was confirmed by microchemical exami- 
nations of the feces, which showed absence of any starch. The aver- 
age coefficient of digestibility of the protein of the whole diet was 81 
per cent and of the fat 92 per cent. 
EXPERIMENTS WITH RAW POTATO STARCH. 
In the experiments with raw potato starch the frozen pudding was 
made up with half the ‘ranean d of starch used in the other experi- 
ments of this series. This was done with the idea of avoiding the 
unpleasant physiological effects experienced by the men when they 
ate large quantities of raw potato starch. In these experiments 
with women, therefore, the diet furnished the following average 
quantities of nutrients and energy per woman per day: Protein, 20 
grams; fat, 37 grams; carbohydrates, 230 grams; energy, 1,330 
calories. The average amount of raw potato starch eaten per 
woman per day was 68 grams. 
The coefficient of digestibility of raw potato starch when corrected 
for accessory food residue was 100 per cent for subject A. T. M.; for 
R. L. P. it was 95 per cent; while for C. M., it was 79 per cent; and 
for EK. M., only 49 per cent. These coefficients of digestibility vary 
in reverse order to the dry weights of the feces and to the proportion 
of carbohydrate in the dry feces; the latter figures were 48 per cent, 
43 per cent, 66 per cent, and 71 per cent, respectively, that is, 
highest in the experiments in which the coefficient of digestibility 
was lowest. None of the subjects experienced any physiological dis- 
comfort during the experiments and all remained in excellent health. 
Subject E. M., who digested the raw potato starch least completely, 
had not been a subject on any previous raw-starch diet, and it is not 
unlikely that she would have digested the starch more completely in 
a second experiment. 
The average coefficient of digestibility of the protein of the entire 
diet was 64.6 per cent and that of the fat, 91.9 per cent. The low 
figure for protein seems to indicate that the digestibility of the pro- 
tein was decreased when the digestibility of the raw potato starch 
was low, but since the amount of protein eaten was small the errors 
involved in the calculation of the protein coefficient are proportion- 
ately large and no definite conclusion can be drawn. Microscopic 
examination showed considerable starch present in all the feces. 
These results are generally similar to those obtained in experiments 
with men eating raw potato starch. In the latter over 99 per cent 
of the potato starch was digested when only 40 grams of starch was 
eaten per man per day, and about 94 per cent when 70 grams of starch 
was eaten per man per day. Among the men, as among the women, 
individuals differed in their ability to assimilate raw potato starch; 
microscopic examination of the feces also showed undigested starch. 
