TABLE OF CONTENTS.

INTRODUCTION

pp. 1-10,

PART I. THE HISTORY OF THE CHICK.

CHAPTER I.

THE STRUCTURE OF THE HEN'S EGG, AND THE CHANGES WHICH TAKE PLACE

UP TO THE BEGINNING OF INCUBATION

PP. 11- 26.

1. The shell. 2. The shell-membrane. 3. The albumen. 4. The vitelling

membrane. 5. The yolk. 6. The yellow yolk. 7. The white yolk. 8. The

white yolk-spheres. 9. The structure of the blastoderm. 10. Recapitulation,

II. The ovarian ovun. 12. The descent of the ovum along the oviduct,

13. The impregnation of the ovum. 14. Segmentation. 15. The formation of

the upper and lower layers.

CHAPTER II.

A BRIEF SUMMARY OF THE WHOLE HISTORY OF INCUBATIO8, pp. 27 -42,

1. The embryo is formed in the area pellucida. 2. The epiblast, moblunt,

and hypoblast. 3. The extension of the blastoderm over the yolk. 4. Th
vascular area.
5. The head-fold and the other fods by means of which the
embryonic sac is formed. 6. The outward shape of the embryo, 7. The
formation of the neural tube and alimentary canal: somatopleure, and splanch
nopleure. 8. The amnion. 9. The amavia,

CHAPTER III.

THE CHANGES WHICH TAKE PLACE DURING THE FIRST DAY OF INCUBATION,

PP. 43-57.

1. Variations in the progress of development. 2. The embryonic shield.
3. The formation of the epiblast, mesoblast and hypoblast. 4. The primitive
streak, the primitive groove. 5. The head-fold, the medullary groove, me-
dullary folds, and notochord. 6. The amnion; the changes taking place in the
three layers. 7. The increase of the head-fold. 8. The closure of the me-
dullary canal. 9, 10. The cleavage of the mesoblast: formation of splanchno-
pleure and somatopleure. II. The protovertebræ. 12. The formation of the
vascular area. 13. Recapitulation.

CHAPTER IV.

THE CHANGES WHICH TAKE PLACE DURING THE SECOND DAY, pp. 58-83.

1. Increasing distinctness and prominence of the embryo. 2. The first cere-

bral vesicle. 3. The increase in the number of protovertebræ. 4. The first
rudiments of the alimentary canal. 5. The formation of the heart. 6. The
formation of blood-vessels; the omphalo-mesaraic veins and arteries, the sinus
terminalis. 7. Changes taking place in the cells of the several layers.
8. The rudiment of the Wolffian duct. 9. Recapitulation of the changes
during the first half of the second day. 10. Increasing prominence of the
embryo; the tail-fold and the lateral folds.
II. Continued closure of the
medullary canal. 12. The optic vesicles. 13. The second and third cerebral
vesicles. 14. Change of position of the optic vesicles. 15. The vesicles of the
cerebral hemispheres. 16. The cranial flexure. 17. The rudiment of the ear, or
auditory sac. 18. Changes in the heart. 19. The primitive aorta and first
pair of aortic arches, the omphalo-mesaraic vessels, the sinus terminalis.
20. The second and third pair of aortic arches. 21. The Wolffian duct.
22. The amnion. 23. Recapitulation.

CHAPTER V.

THE CHANGES WHICH TAKE PLACE DURING THE THIRD DAY, pp. 84-140.

1. The diminution of the albumen. 2. The spreading of the opaque and

vascular areas. 3. The vascular area. 4. The continued folding in of the

embryo. 5. The increase of the amnion. 6. The change in the position of

the embryo. 7. The curvature of the body. 8. The cranial flexure.

9. Growth of the vesicles of the cerebral hemispheres; the third ventricle,

pineal gland, infundibulum and pituitary body, the cerebellum and medulla

oblongata. 10. Changes in the spinal cord. II. The formation of the eye.

Histological changes in the retina, optic nerve, and lens. 12. The formation

of the ear.
13. The nasal pits. 14. The visceral clefts and folds.
15. The

aortic arches. 16. Changes in the heart; the Ductus Cuvieri and cardinal

veins. 17. The folding in of the alimentary canal; the formation of the tail.

18. The lungs. 19. The liver. 20. The pancreas and spleen. 21. The

thyroid body. 22. Changes in the trunk of the embryo. 23. Separation of

the muscle-plates from the proto vertebræ. 24. Growth of the intermediate

cell-mass. 25. The cranial nerves. 26. The Wolffian duct. 27. Recapi-

tul

CHAPTER VI.

THE CHANGES WHICH TAKE PLACE DURING THE FOURTH DAY, pp. 141–173.

I. Appearances on opening the egg. 2. Growth of the amnion.

3. Narrowing of the splanchnic stalk. 4. Increase in the cranial flexure.

5. The first appearance of the limbs. 6. Growth of the head. 7. Changes

in the nasal pits. 8. Formation of the mouth. 9. The cranial nerves.

The allantois. 11. Changes in the protovertebræ; the spinal ganglia.

12. The secondary segmentation of the vertebral column. 13. Changes in

the notochord. 14. Ossification of the vertebræ.
15. The ribs. 16.

IO.

The

21.

Changes in the muscle-plates. 17. The Wolffian body and duct. 18.

duct of Müller. 19. The kidneys.
20. The ovaries and testes.

Changes in the arterial system. 22. Changes in the venous system; the

veins of the liver. 23. Changes in the heart; the ventricular septum.

24. Recapitulation.

CHAPTER VII.

THE CHANGES WHICH TAKE PLACE ON THE FIFTH DAY, pp. 174-199.

1. Appearances on opening the egg. 2. The growth of the limbs.

3. The cranium; the investing mass and trabecula. 4. Changes in the
face; formation of the nose and nasal passages. 5. Appearance of the anus.
6. Changes in the spinal cord; the formation of the grey and white columns,
and of the posterior and anterior fissures. 7. Changes in the heart; the
rudiment of the auricular septum, the division of the bulbus arteriosus into
aorta and pulmonary artery, the formation of the semilunar valves. 8. Changes
in the heart during the sixth day. 9. Subsequent changes in the heart; the
completion of the auricular septum, the arrangement of the openings of the
venæ cavæ. 10. Histological differentiation; the fate of the three primary
layers. II. Recapitulation.

CHAPTER VIII.

FROM THE SIXTH DAY TO THE END OF INCUBATION, pp. 200-224.

I. The commencement of distinct avian differentiation. 2. The fœtal

appendages during the sixth and seventh days. 3. During the eighth, ninth

and tenth days. 4. From the eleventh to the sixteenth day. 5. From the

sixteenth day onwards. 6. The changes in the general form of the embryo

during the sixth and seventh days. 7. During the eighth, ninth and tenth

days. 8. From the eleventh day onwards; feathers, ossifications. 9. Changes

in the venous system before and after the commencement of pulmonary respi-

ration. 10. Changes in the arterial system, the modifications of the aorti

arches. 11. Summary of the chief phases of the circulation. 12.

clusion from the egg.

CHAPTER IX.

THE DEVELOPMENT OF THE SKULL, pp. 225-238.

I, 2. The primordial cranium. 3, 4. The investing mass of Rathke.
5. The trabeculæ cranii. 6. The cartilages of the first visceral arch. 7.

IO.

The maxillary process. 8. The mandibular arch. 9. The hyoid arch.
The cartilages of the third visceral arch. II. Changes in the cranium during
the fifth and sixth days. 12. During and after the seventh day. 13. The
condition of the cranium at about the middle of the second week. 14. Ecto-
steal and endosteal ossifications of the cartilaginous cranium.

15. Formation
of the membrane bones. 16. Progress of ossification during the second and
third weeks. 17. Fenestration of the ethmo-presphenoid cartilage. 18. Ossifi-
cations in the prootics and alisphenoid. 19. Changes in the basitemporals.
Formation of the vomer. 20. The changes which take place immediately
after exclusion from the egg. 21. Further changes in the splint bones.
Coalescence of the bones after birth. Table of bones classified according to
their mode of ossification.

APPENDIX.

PRACTICAL INSTRUCTIONS FOR STUDYING THE DEVELOPMENT OF THE CHICK,

pp. 239-267.

III.

I. Incubators. II. Examination of a 36 to 48 hours embryo.

Examination of an embryo of about 48-50 hours. IV. Of an embryo at the

end of the third day. V. Of an embryo of the fourth day. VI. Of a

blastoderm of 20 hours. VII. Of an unincubated blastoderm. VIII. Of the

process of segmentation. IX. Of the later changes of the embryo. X. Study

of the development of the blood-vessels.

ERRATUM.

p. 124, in the description of Fig. 39 B, for 'Superior vertebral' substitute

'Jugular.'

2.

DIAGRAMMATIC Section of an Unincubated Fowl's Egg

A. Yellow yolk-sphere filled with fine granules. B. White yolk-
spheres and spherules of various sizes and presenting different ap-
pearances

3. Section of a Blastoderm of a Fowl's Egg at the commencement of
Incubation.

15

18

4.

Section through the Germinal Disc of the ripe Ovarian Ovum of a
Fowl while yet enclosed in its Capsule.

19

5. Surface Views of the early Stages of the Segmentation in a Fowl's Egg

22

6. Surface View of the Germinal Disc of a Hen's Egg during the later Stages of Segmentation

7. Section of the Germinal Disc of a Fowl during the later Stages of Segmentation

8. A to N. A series of purely diagrammatic representations introduced to facilitate the comprehension of the manner in which the body of the embryo is formed, and of the various relations of the yolk-sac, amnion and allantois

23

24

29-32

9. Diagrammatic Longitudinal Section through the Axis of an Embryo. 33

IO.

Section of a Blastoderm at right angles to the long axis of the
Embryo after eight hours' Incubation.