x CONTENTS. 



PAGE 



The Spinal Cord and Brain, 



Plakodes, 



The Nasal Pits and Olfactory Nerves, . 



The Eye, 



The Otocyst, 



The Early History of the Mesoderm, . 

 Somatopleure and Splanchnopleure, . . 



The Embryonic Ccelom, 



The Mesenchyma, 



The .Origin of the Blood-vessels and Blood, 9 



The Blood-corpuscles, 



The Origin of the Heart, 9 6 



The Germinal Area, 9 



The Main Vessels of the Area Vasculosa, ... 97 



The Aortic System, 99 



The Venous System, 102 



The Lymphatic System, I0 5 



The Liver, I0 7 



The Pancreas, I0 7 



The Excretory Organs, Io8 



The Urogenital Ducts, .no 



The Allantois, IIX 



The Trophoderm, "4 



The Umbilical Cord, ......,;..,.. 115 



The Chorion and Amnion, 1 1 7 



CHAPTER III. THE HUMAN EMBRYO, "8 



Calculation of the Age of the Human Embryo, . . . . 118 



The Classification of the Early Stages, 119 



Hypothetical Development of the Blastodermic Vesicle in Primates, 122 



Relations of the Embryo to the Uterus: the Two Stages, 124 



Ovum of a Monkey in the Second Stage, 127 



Human Embryo in the Second Stage, 128 



The Embryo of a Gibbon in the Third Stage, 131 



Human Embryo in th Fourth Stage with the Medullary Plate, 134 



Human Embryo in the Fifth Stage with Open Medullary Groove, 136 



Human Embryo in the Sixth Stage with Medullary Canal, . . . 137 



Human Embryo in the Seventh Stage with One Gill-cleft Showing Externally, ... 1 40 



Human Embryo in the Eighth Stage with Two Gill-clefts Showing Externally, 141 



Human Embryo in the Ninth Stage with Three Gill-clefts Showing Externally, . . .- 143 



Human Embryo in the Tenth Stage with Four Gill-clefts Showing Externally, 146 



Human Embryo in the Eleventh Stage with the Cervical Sinus in Formation, 147 



Human Embryos of the Fourth Week to the Fourth Month, 148 



CHAPTER IV. STUDY OF THE SEGMENTATION OF THE OVUM AND OF THE BLASTODERMIC YKSI- 



CLE IN MAMMALS, ; 1 60 



The Maturation, Fertilization, and Segmentation of the Ovum in White Mice, 160 



Method of Obtaining Blastodermic Vesicles from the Rabbit, 166 



Study of Rabbit Blastodermic Vesicles in Alcohol, 167 



CHAPTER V. STUDY OF YOUNG CHICK EMBRYOS, 1 74 



Method of Obtaining Embryos, ; 1 74 



