The development of these two main digestive glands as diverticula from the intestinal canal also explains the direct continuity of the mucous membrane of their ducts with that lining the duodenum, a fact which is of considerable importance in the pathological extension of mucous inflammations from the intestine to the duct system of the glands. =Development of the Pancreas in Lower Vertebrates.=--In the embryo of the _sheep_ two pancreatic buds are found, but the duct of the dorsal (proximal) outgrowth (duct of Santorini) subsequently fuses entirely with the main duct. In the _cat_ there are likewise two pancreatic outgrowths. In the _chick_ three pancreatic buds are visible about the fourth day. _Amphibia_ likewise present three embryonic pancreas buds. The ventral (distal) outgrowth is double, the two portions proceeding symmetrically from each side of the hepatic duct. The single dorsal outgrowth is derived directly from the duodenal epithelium. Later on all these outgrowths fuse to form the single adult gland. _Fish_ also possess several (up to four) embryonic pancreatic outgrowths. Recently in human embryos of 4.9 mm. cervico-coccygeal measure three pancreatic outgrowths have been observed, all entirely distinct from each other, one dorsal, budding from the epithelium of the primitive duodenum and two ventral, proceeding from the grooved gutter which represents the primitive ductus choledochus at this period. In embryos of from 6 to 10 mm. the two ventral outgrowths have already fused, hence only two buds, a single ventral and a dorsal, are now encountered.[4] [4] Iankelowitz, Arch. f. Mikr. Anat., Bd. 46, 1895. These observations place the development of the human pancreas in line with the triple pancreatic outgrowths, two ventral and one dorsal characteristic of the majority of the lower vertebrates, which have been hitherto carefully examined. The ventral or distal bud is probably double in the majority of vertebrates. The two segments fuse, however, so early that the derivation of the pancreas from a double outgrowth, as described above for the human embryo, practically obtains. In forms in which the adult gland presents a number of separate openings into the duodenum (cf. p. 118), the development would probably show multiple embryonic outgrowths from the intestinal hypoblast. In any case the dorsal pancreatic bud appears to have developed in the vertebrate series before the ventral outgrowth and to be hence phylogenetically the older structure. COMPARATIVE ANATOMY OF THE PANCREAS.