One hundred years later the obscure importance of the absorbing alimentary tract must still be emphasized. In the words of a popular textbook: the energy that controls absorption resides in the wall of the intestine, presumably in the epithelial cells and constitutes a special form of imbibition which is not yet understood. Thus the dignity of the living structures still remains unchallenged.

The uncertainty regarding the acidity of the gastric juice which still prevailed twenty years after Young's paper was. published has already been mentioned. Even as late as 1812 Montegre insisted that what was supposed to be gastric juice is nothing but swallowed saliva. An American, Professor Smith, suggested that digestion is performed "by the veins of the stomach, and by the liver." Vague ideas like these, in contrast with modest experimental inquiries illustrated by the monograph which we have reviewed in some detail, led Dr. Beaumont to remark: