Development of Aortal Arterial System 63 II. Demonstration of Intestinal Rotation in the Lower Mammalia 67 Peritoneal and Visceral Relations in the Infra-colic Compartment of the Abdominal Cavity in the Adult 74 Part II. ANATOMY OF THE PERITONEUM IN THE SUPRA-COLIC COMPARTMENT OF THE ABDOMEN 99 1. STOMACH AND DORSAL MESOGASTRIUM 100 _a._ Changes in Position of Stomach 102 _b._ Changes in Direction and Extent of Dorsal Mesogastrium 103 _c._ Development of Spleen and Pancreas in the Dorsal Mesogastrium and Changes in the Disposition of the Great Omentum 108 1. Development of Spleen 108 2. Development of Pancreas 111 Development of Pancreas in Lower Vertebrates 115 Comparative Anatomy of Pancreas 116 Pyloric Caeca or Appendices 119 Peritoneal Relations of Pancreas 122 Comparison of Embryonal Stages during the Development of the Human Dorsal Mesogastrium, Spleen and Pancreas with the Permanent Adult Condition of the same Structures in Lower Mammalia 126 1. Spleen, Pancreas and Great Omentum of Cat 127 2. Relation of Great Omentum to Transverse Colon, Transverse Mesocolon and Third Part of Duodenum 129 2. VENTRAL MESOGASTRIUM AND LIVER 140 I. _A._ Development of Liver 141 _B._ Comparative Anatomy of Liver 144 _C._ Development of Vascular System of Liver 145 Comparative Anatomy of the Hepatic Venous Circulation 154 II. Ventral Mesogastrium 163 Peritoneal Relations of Liver 167 Relation of Hepatic Peritoneum to the "Lesser Sac" 174 Caudal Boundary of Foramen of Winslow 178 Pancreatico-gastric Folds 181 PART III. LARGE AND SMALL INTESTINE, ILEO-COLIC JUNCTION AND CAECUM 189 I. GENERAL REVIEW OF MORPHOLOGY AND PHYSIOLOGY OF THE VERTEBRATE INTESTINE 190 I. Midgut or Small Intestine 192 Intestinal Folds 193 Divisions of Small Intestine 194