[Sidenote: Recent discoveries concerning digestive juices]
Within the past few years many remarkable discoveries have been made in
regard to the secretion of the various digestive juices. Until some ten
or fifteen years ago it was believed that the secretion of the digestive
juices depended wholly upon the presence of food in the alimentary
canal. The recent discoveries in this branch of physiology are to be
accredited chiefly to Professor Palloff, a Russian scientist, and his
co-workers. The facts that are now known regarding this part of Nature's
work are essentially as follows:
The secretion of the various substances which make up the digestive
fluids of the body depend upon two kinds of stimuli: