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energy. 3. Fatty substances, also containing carbon, hydrogen, 
and oxygen, which supply heat and energy in an especial degree. 
Food in the alimentary canal is of no more use than when outside 
the body. To become useful it must be rendered soluble and passed 
into the blood and thence to all parts of the body. It is the function 
of digestion to bring about this change. 
The lecturer dealt in order with the different portions of the 
alimentary canal and the functions of each. Into the mouth open 
the ducts of the salivary glands. The presence of food in the 
mouth by reflex action causes these glands to secrete saliva, a 
message being sent along the nerves to a centre in the brain, and 
a reply message being received by the glands. The function of 
the saliva is not only, as in the case with carnivorous animals, 
to assist in mastication and in swallowing ; it also has the power 
of transforming starch into sugar, thus rendering it soluble. The 
lecturer showed this by an experiment. He took into his mouth 
a small quantity of starch and water, and after ejecting it into a 
test tube proved that the starch had entirely disappeared. The 
walls of the stomach contain glands which at the presence of food, 
or the mere smell or thought of food with a hungry subject, secrete 
the gastric juice. This contains dilute hydrochloric acid and other 
substances which in turn dissolve and break up other constituents 
of the food. As the process in the stomach is completed small 
portions at a time are allowed to pass by a valve into the small 
intestine into which open the bile ducts from the liver and the 
ducts from the pancreas. The secretion of the last is brought about 
by “special messenger,’ and not by the telephone method of 
reflex action. A constituent of the partly digested food passes 
into the blood and thence reaches the pancreas, which is excited 
into active secretion. By the pancreatic juice the process of 
conversion of starch into sugar is completed. In the intestine 
the nitrogenous substances in the food are converted into proteids 
suitable for absorption by the blood. Fats are also rendered 
soluble by conversion into soaps or into emulsions, and are absorbed. 
Thus useful constituents are removed from the food during its 
passage along the great lengths of the small and large intestines. 
After the lecture some interesting replies were given by Prof. 
Starling to questions asked. As regards the relative value of 
different foods, he said that meat was by no means of the great 
importance generally attributed to it. As shown by various races 
of men, equally efficient nourishment could be obtained from a 
diet consisting solely of vegetable food. In the case of growing 
children he considered it wiser to run no risk and to give them 
animal food ; but the full-grown labourer could subsist perfectly 
well on bread and butter and leave the steak for the children. 
