VII 



p. 122 — Amphioxus in the light of my theory, p. 124— The 

 mouth of Amphioxus, p. 126 — First pair of gill-pouches, 

 p. 127 — Anterior spinal nerves, p. 129 — Neuropore and 

 praeoral lobe in Ascidians, p. 131 — Mouth of Ascidians,p. 

 133 — Segmentation in Ascidians, p. 133. 



History of the Vertebrate head, p. 135 — Animal pole of 

 egg and blast ula, p. 135 — Head of Amphioxus, p. 137 — Head 

 of Petromyzon, p. 138 — Amphibian head. p. 144 — Head 

 of Selachians, p. 147 — Head of Amniotes, p. 152 — General 

 conclusions, p. 153 — Hypoglossus homologous in Verte- 

 brates? p. 154. 



III. Gastrulation and earliest Development .... p. 156 



Fate of the animal pole, p. 157 — Teleostean eggs, p. 

 157 — Amphibian eggs, p. 159 — Acrania and Craniata, p. 

 160 — Gastrulation, p. 161 — Different views, p. 163 — 

 Theory of concrescence, p. 166 — Objections, p. 167 — Ex- 

 periments, p. 168 — Spina bifida, p. 169 — Invagination of 

 ectoderm cells ? p. 170— LwOFF's views, p. 173— HUBRECHrs 

 speculations, p. 174 — Conception arising from my theory, p. 

 175 — Eccentric closure of the blastopore, p. 176 — Different 

 views on movement of blastopore border, p. 177 — Conclu- 

 sions from pricking experiments, p. 179 — Interpretation 

 of the results, p. 185 — Comparison with Annelids, p. 

 185 — Displacement of the endoderm area, p. 188 — Inter- 

 pretation of the eccentric closure of the blastopore, p. 190 — 

 Summary, p. 192 — Relation of anas and blastopore, p. 

 193 — Different views on Anurans, p. 193 — Rana escu- 

 lenta, p. 195 — Different views on Urodelans, p. 198 — Am- 

 blysfoma tigrinum, p. 199 — Different interpretations, p. 



203 — Primary relation between anus and blastopore ? p. 



204 — Secondary relation between anus and blastopore, 

 p. 206 — Perianal and periporal growing zones, p. 206 — In- 

 terference of both with the gastrulaiion, p. 207 — Formation 

 of the tail, p. 210 — Difference between Urodelans, Anu- 

 rans and Selachians, p. 212 — Mesoderm of Vertebrates, 

 p. 213 — Notochord, p. 215 — Gill slits, p. 216. 



Literature . p. 217. 



