It will be seen that, among the animals examined, there is much diversity in the manner of entry of the pancreatic and bile ducts (see PL I.). There may be a common duct, as in the monkey, sheep, rat, and mouse, or two ducts entering side by side, as in the cat. The bile and pancreatic ducts may be separated by a considerable length of gut, as in the pig, rabbit, and cow, in which case the bile duct is always the higher of the two. An accessory pancreatic duct may be present; this may enter above the common duct, as in man and the stoat, or between the bile and pancreatic ducts, as in the dog and the guinea-pig.
With regard to Brunner's glands, these observations on the whole support Villemin's contention that the glands cease where the pancreatic duct enters, whether singly or in common with the bile duct, though small variations about this level are found. In the pig and the guinea-pig, however, the glands extend half a metre or more beyond this level, though the gland mass at the beginning of the duodenum is unusually large in the pig. The Carnivores examined all possess a short compact gland mass, just reaching or falling short of the common duct; but in the dog the mass fails to reach even the bile duct entry.
I wish to thank Sir Charles Sherrington and the late Professor Georges Dreyer for facilities accorded me in their departments, Professor Florey and Dr. H. E. Harding, of Sheffield, for the human material, and Colonel Hamerton, C.M.G., D.S.O., for animal material from the Zoological Gardens. I also wish to thank Mr. W. Chesterman and Mr. T. Marsland for much help in section-cutting and staining.