The development of the carp, cyprinus carpio. II. The development of the liver‐pancreas, the Islands of langerhans, and the spleen

The first stage in the formation of the liver is two ventrolateral evaginations of the mid‐gut at the time of hatching. From the undifferentiated cells branching from the liver duct the pancreas cells arise, but do not assume adult character until the carp is about 41 mm. long. The islet makes its first appearance in the region of the pancreatic duct at the 8‐mm. stage and shows no transitional stages. In the mesenchyme itissue dorsal to the intestine the spleen arises, and is finally completely surrounded by the liver‐pancreas.