22 
THE NATURAL SCIENCE JOURNAL. 
same empirical formula as caue sugar 
but rather resembling glucose in its reac¬ 
tions. The same experiment performed 
with raw potato, or other forms of un¬ 
cooked starch, will neither cause a sweet 
taste to develop nor yield the reactions of 
sugar. The explanation of these phe¬ 
nomena is that saliva contains a peculiar 
ferment called ptyalin, which, at or near 
the temperature of the body, has the 
power of converting starch into maltose, 
while it is not sufficiently powerful to 
penetrate the envelope of cellulose in 
which the starch granules are contained. 
Cooking ruptures these little envelopes, 
the change being, on a microscopic scale, 
the same as that which occurs visibly 
when corn is popped. 
The secretion of the stomach has no 
action on starch, though digestion by 
means of ptyalin, proceeds for some 
time after food is swallowed. AVlien 
food passes out of the stomach, from 
two to seven hours after a meal, it enters 
the intestine and is subjected to the 
action of a secretation flowing from the 
pancreas. This secretion has very com¬ 
plex functions but one of them is essen¬ 
tially the same as that of saliva, the 
conversion of starch into maltose. The 
pancreatic ferment, however, is at least 
forty times as energetic as ptyalin and it 
digests uncooked starch as well as that 
whose cellulose has been ruptured by 
cooking. A banana, for instance, may 
have the small amount of sugar which it 
contains, abstracted in the stomach, but 
the bulk of its substance, consisting of 
raw starch, remains undigested till the 
intestine is reached. As the result of 
starch digestion, the body is supplied 
with a large amount of malt sugar, it 
also has a greater or less amount of cane 
sugar, and especially in the case of 
infants and invalids, considerable milk 
sugar introduced with food. These vari¬ 
ous sugars all have the same proportion¬ 
ate amount of carbon, hydrogen and 
oxygen in the molecule, and all are modi¬ 
fied so as to produce glucose, by the 
secretion of the intestine itself. 
We may readily infer the tremendous 
importance of glucose in the system,from 
the fact that two entirely distinct secre¬ 
tions, the saliva and the pancreatic juice 
take part in the first step of the digestive 
process and that this preliminary diges¬ 
tion is completed by the secretion of 
innumerable microscopic glands in the 
intestine. We may also note that the 
salivary glands which secrete ptyalin are 
four in number and are anatomically 
separate, so that a failure of this secre¬ 
tion is almost unknown. 
The practical deductions are obvious. 
Glucose, provided it be glucose and free 
from impurities, by no means deserves 
the odiom in which it is held. Mastica¬ 
tion and the mixture of saliva with food 
are necessary digestive acts. Sugars, 
including candy, must be regarded not as 
essentially harmful substances but as 
more or less perfectly digested foods. 
While, in general, it is unwise to perform 
for the body a digestive or other function 
which it can perform itself, there can be 
no objection to a moderate use of sugar 
and candy, especially when the desire 
represents a normal appetite. The com¬ 
mon mistake in regard to the use of 
candy, is to abstain from it till the natu¬ 
ral appetite has become exaggerated into 
a craving which leads to gluttony. Candy 
and other sweets should be eaten at the 
close of a meal, so as not to interfere 
with the appetite for ordinary plain food. 
