CONTENTS xv 



Eclunodermata generally The formation of layers The frequent presence of a 

 right madreporic pore The Bipinnaria larva : its Brachiolaria phase and its 

 metamorphosis The occasional presence of a right hydrocoele The metamor- 

 phosis of Astropectinidae The formation of organs in Asterina gibbosa Peculiar- 

 ities in the development of Cribrella and tiol aster Experiments on the eggs of 

 Asteroidea Driesch's argument in favour of the existence of an entelechy 

 Herbst's experiments in solution of sulphocyanide of potassium The development 

 of Ophiothrix fragilis as a type of the Ophiuroidea The Ophiopluteus larva 

 and its affinities with the Bipinnaria larva The metamorphosis of the Ophio- 

 pluteus The development of the calcareous skeleton and of the genital organs in 

 Amphiura squamata The development of Ophiura brevispina The development 

 of Echinus esculentus as a type of the Echinoidea Methods of obtaining, 

 fertilizing, and rearing the eggs The Echinopluteus larva and its affinities with 

 the Ophiopluteus larva The metamorphosis of the Echinopluteus larva The 

 ammotic cavity possibly originally a part of the larval stomodaeum Peculiar 

 features in the development of Echinocijamus, Mellita, and Echinoeardium 

 Experiments on the eggs of Echinoidea -The results of hybridization : (1) between 

 dill'erent classes, (2) between different orders, (3) between different species The 

 artificial parthenogenesis of eggs and the means of producing it Effects of 

 separating the blastomeres of the developing egg and of cutting up the blastulae 

 The effects of chemical substances on the development of the egg The Lithium 

 larva and the explanation thereof Formative stimuli The development of 

 Synapta diyitata as a type of the Holothuroidea The Auricularia larva : its 

 resemblances to the Bipinnaria larva The metamorphosis of the Auricularia 

 larva The pupal stage and its change into the adult Holothuroid The formation 

 of the genital organs in Synapta vivipara and in Cucumaria glacial-is The 

 development of Holothuria tubulosa The development of Cucumaria planci The 

 post-larval development of Antarctic species of Cucumaria The development of 

 Antedon rosacea as a type of the Crinoidea The formation of layers The free- 

 swimming larva The metamorphosis of this larva into the fixed Pentacrinoid 

 larva The attainment of the adult form Ancestral significance of the Echino- 

 derni larva The Dipleurula ancestor of Echinodermata and its relation to the 

 Ctenophore-like ancestor of Annelida and Mollusca The interpretation of Echino- 

 derm metamorphosis and the reason for the divergence of the Asteroid and 

 Grinoid stocks The causes of the evolution of Ophiuroidea, Echinoidea, and 

 Holothuroidea ........ Page 456 



CHAPTER XVII 



PROTOCHORDATA 



Meaning of the term Protochordata The development of Balanoglossus davigerus as 

 a type of the Hemichorda The development and metamorphosis of the New 

 England Tornaria larva The metamorphosis of the Nassau Tornana larva 

 The Tornaria larva of the Pacific coast -The development of Dolichoglossus 

 koivalcvskii The development of Dolichoylossus pusillus The affinities of the 

 Hemichorda to Echinodermata The development of Amphioxus lanceolxl//* 

 as a type of the Cephalochorda -The process of gastrulation The formation of 

 the coelom The formation of the mouth and first gill-slits The larva and its 

 primary gill -slits The formation of the sclerotomes, nephridia, and genital 

 organs The formation of the secondary gill-slits and the metamorphosis of iln 

 j arva The evidence in favour of the affinity of Amphioxus with the Hemichorda 



