CONTENTS 



CHAPTEE I 

 INTRODUCTION" 



Scope of Embryology— Growth, maturation, and conjngation of the germ-cells— Sex- 

 chromosomes and their bearing on theories of heredity— Recapitulation theory 

 of development and the evidence in its favour— Embryonic and larval phases of 

 development and their mutual relationship— Factors modifying the course of 

 development . . . . . . . Page 1 



CHAPTEE II 



PRACTICAL HINTS 



Methods of preserving embryos— Methods of embedding embryo for section- 

 cutting and of orientating them so that the sections shall be cut in a known 

 direction ........ Page 32 



CHAPTEE III 



PORIFERA 



The development of Sycaiidra raphanus as a type of the Calcarea : the Blastnla, 

 Amphiblastula, and Ascon stages in its development — The development of other 

 sponges {Oscarella, Plakina, Esperia, Spongilla, Clathrina, Leucosolenia) — 

 The development of the gemmiile of Ephydatia — The ancestral history of 

 sponges ......... Page 37 



CHAPTEE IV 



COELENTERATA 



The development of Tuhularia as a type of the Hydrozoa — The development of the 

 eggs of free-swimming medusae — The development of the gonophore of Tiibularia 

 and of the medusa of Podocoryne — Other gonophores — The development of 

 . Siphonophora, Narcomedusae, and Trachymedusae — The development of Aurelia 

 aS a type of the Scyphozoa — The development of Pelagia — The development of 

 Urticina as a type of the Actinozoa — The development of Actinia termudensis — 

 The larvae of Zoanthidae and Cereanthidae — The development of Alcyonaria — The 

 development of the skeleton of Caryophyllia — The development of Beroe as a type 



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