x CONTENTS. 



PAGE 



Hypothetical Development of the Blastodermic Vesicle in Primates, 116 



Relations of the Embryo to the Uterus, Il8 



Ovum of a Monkey in the Second Stage, 121 



Human Embryo in the Second Stage 123 



Embryo of a Gibbon in the Third Stage 127 



Human Embryo in the Fourth Stage with Medullary Plate, 129 



Human Embryo in the Fifth Stage with Open Medullary Groove 131 



Human Embryo in the Sixth Stage with Medullary Canal, 132 



Human Embryo in the Seventli Stage with One Gill-cleft, 135 



Human Embryo in the Eighth Stage with Two Gill-clefts, 135 



Human Embryo in the Ninth Stage with Three Gill-clefts 13S 



Human Embryo in the Tenth Stage with Four Gill-clefts, 141 



Human Embryo in the Eleventh Stage with Limb-buds, 142 



Human Embryo of Twenty-six Days 143 



Human Embryo of Twenty-eight Days, 143 



Embryos of the Second, Third, and Fourth Months, 145 



Chapter IV. — Study of Pig Embryos, 157-26S 



Methods of Obtaining Embryos, 157 



The Making of Serial Sections, 158 



Selection of the Planes of Section and the Stages for Practical Study, 158 



The Study of the External Form, 159 



Pig Embryo of 10 mm , 160 



Pig Embryo of 12 mm. General Anatomy, 162 



Pig Embryo of 15 mm. (External Form) 17° 



Pig Embryo of 20 mm. (External Form), 17 1 



Pig Embryo of 12 mm. (Studied in Sections), 173 



The Study of Transverse Sections, 1 75 



Section through the Upper Part of the Otocyst, 175 



Section through the Lower Part of the Otocyst, 181 



Section through the First Gill-cleft, 184 



Section through the Second Gill-cleft, 1S7 



Section through the Third Gill-cleft 190 



Section through the Fourth Gill-cleft 193 



Section through the Anterior Limbs and Heart, I95 



Section to show the Brachial Plexus, I99 



Section through the Stomach and Liver, 201 



The Study of Sagittal Sections, 205 



Median Section of the Head, 205 



Section of the Head through the Principal Ganglia, 208 



The Study of Frontal Sections, 211 



Section through the Trigeminal Roots 212 



Section through the Acusttco-facial Ganglion, • 213 



Section through the Otocyst 214 



Section through the Dorsal Vertebne, 215 



Pig Embryo of 9 mm. (Studied in Sections), 217 



Transverse Section through the Branchial Arches, 217 



Sagittal Section to the Right of the Median Plane, .... 219 



Frontal Section through the Mid-brain and Fore-brain, 222 



Frontal Section through the Umbilical Opening, 223 



Frontal Section through the Second and Third Gill-clefts, 227 



Pig Embryo of 6 mm. (Studied in Sections), 228 



Pig Embryo of 17 mm. (Studied in Sections) 231 



Transverse Section through the Lungs, 23 1 



Section through the Wolffian Body and Genital Gland, 235 



Section through the Kidney 237 



Frontal Section of the Umbilical Cord, 239 



Pig Embryo of 20 mm. (Studied in Sections), 240 



Transverse Section through the Snout, 240 



Transverse Section through the Lower Part of the Neck, 241 



Transverse Section through the Lungs 244 



Transverse Section through the Posterior Limbs, 247 



Transverse Section through the Mammary Anlage, 249 



