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قراءة كتاب The Origin of Vertebrates
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THE
ORIGIN OF VERTEBRATES
BY
WALTER HOLBROOK GASKELL
M.A., M.D. (CANTAB.), LL.D. (EDIN. AND McGILL UNIV.); F.R.S.; FELLOW OF TRINITY
HALL AND UNIVERSITY LECTURER IN PHYSIOLOGY, CAMBRIDGE; HONORARY FELLOW
OF THE ROYAL MEDICAL AND CHIRURGICAL SOCIETY; CORRESPONDING MEMBER
OF THE IMPERIAL MILITARY ACADEMY OF MEDICINE, ST. PETERSBURG, ETC.
LONGMANS, GREEN, AND CO.
39 PATERNOSTER ROW, LONDON
NEW YORK, BOMBAY, AND CALCUTTA
1908
All rights reserved
CONTENTS
| PAGE | |
| Introduction | 1 |
| CHAPTER I | |
| The Evidence of the Central Nervous System | |
| Theories of the origin of vertebrates—Importance of the central nervous system—Evolution of tissues—Evidence of Palæontology—Reasons for choosing Ammocœtes rather than Amphioxus for the investigation of this problem—Importance of larval forms—Comparison of the vertebrate and arthropod central nervous systems—Antagonism between cephalization and alimentation—Life-history of lamprey, not a degenerate animal—Brain of Ammocœtes compared with brain of arthropod—Summary | 8 |
| CHAPTER II | |
| The Evidence of the Organs of Vision | |
| Different kinds of eye—Simple and compound retinas—Upright and inverted retinas—Median eyes—Median or pineal eyes of Ammocœtes and their optic ganglia—Comparison with other median eyes—Lateral eyes of vertebrates compared with lateral eyes of crustaceans—Peculiarities of the lateral eye of the lamprey—Meaning of the optic diverticula—Evolution of vertebrate eyes—Summary | 68 |
| CHAPTER III | |
| The Evidence of the Skeleton | |
| The bony and cartilaginous skeleton considered, not the notochord—Nature of the earliest cartilaginous skeleton—The mesosomatic skeleton of Ammocœtes; its topographical arrangement, its structure, its origin in muco-cartilage—The prosomatic skeleton of Ammocœtes; the trabeculæ and parachordals, their structure, their origin in white fibrous tissue—The mesosomatic skeleton of Limulus compared with that of Ammocœtes; similarity of position, of structure, of origin in muco-cartilage—The prosomatic skeleton of Limulus; the entosternite, or plastron, compared with the trabeculæ of Ammocœtes; similarity of position, of structure, of origin in fibrous tissue—Summary | 119 |
|
CHAPTER IV |
|
| The Evidence of the Respiratory Apparatus | |
| Branchiæ considered as internal branchial appendages—Innervation of branchial segments—Cranial region older than spinal—Three-root system of cranial nerves: dorsal, lateral, ventral—Explanation of van Wijhe's segments—Lateral mixed root is appendage-nerve of invertebrate—The branchial chamber of Ammocœtes—The branchial unit, not a pouch but an appendage—The origin of the branchial musculature—The branchial circulation—The branchial heart of the vertebrate—Not homologous with the systemic heart of the arthropod—Its formation from two longitudinal venous sinuses—Summary | 148 |
| CHAPTER V | |
| The Evidence of the Thyroid Gland | |
| The value of the appendage-unit in non-branchial segments—The double nature of the hyoid segment—Its branchial part—Its thyroid part—The double nature of the opercular appendage—Its branchial part—Its genital part—Unique character of the thyroid gland of Ammocœtes—Its structure—Its openings—The nature of the thyroid segment—The uterus of the scorpion—Its glands—Comparison with the thyroid gland of Ammocœtes—Cephalic generative glands of Limulus—Interpretation of glandular tissue filling up the brain-case of Ammocœtes—Function of thyroid gland—Relation of thyroid gland to sexual functions—Summary | 185 |
| CHAPTER VI | |
| The Evidence of the Olfactory Apparatus | |
| Fishes divided into Amphirhinæ and Monorhinæ—Nasal tube of the lamprey—Its termination at the infundibulum—The olfactory organs of the scorpion group—The camerostome—Its formation as a tube—Its derivation from a pair of antennæ—Its termination at the true mouth—Comparison with the olfactory tube of Ammocœtes—Origin of the nasal tube of Ammocœtes from the tube of the hypophysis—Direct comparison of the hypophysial tube with the olfactory tube of the scorpion group—Summary | 218 |
| CHAPTER VII | |
| The Prosomatic Segments of Limulus and its Allies | |
| Comparison of the trigeminal with the prosomatic region—The prosomatic appendages of the Gigantostraca—Their number and nature—Endognaths and ectognath—The metastoma—The coxal glands—Prosomatic region of Eurypterus compared with that of Ammocœtes—Prosomatic segmentation shown by marks on carapace—Evidence of cœlomic cavities in Limulus—Summary | 233 |