THE ADOLESCENT PERIOD. 89 



the anterior surface of the septum form a follicular epithelial 

 investment. 



These knobs, each of which is a solid mass of enlarged epithe- 

 lial cells, gradually increase in size, extending forwards until 

 they ultimately occupy the whole length of the segments. The 

 cavities in which they lie, really parts of the myoccel (Fig. 41, cm), 

 widen considerably to allow for this increased size, and in speci- 

 mens of about 15 or 16 mm. length become shut off completely from 

 the rest of the myoccel. Boveri has proposed the term gonotome 

 for this portion of the somite, which is specially connected with 

 the reproductive organs, and which is only found in the somites 

 from the tenth to the thirty-fifth or thirty-sixth, in which these 

 organs lie ; he has further directed attention to the fact that the 

 position at which the reproductive organs appear in Amphioxus, 

 close to the line of separation between myoccel and splanch- 

 noccel, corresponds very nearly to that which they hold, in the 

 earlier stages of their development, in the higher Vertebrates. 



List of the more important Publications dealing with 

 the development of Amphioxus. 



Boveri, T. : ' Ueber die Bildungsstiitte der Geschlechtsdriisen und die Entste- 



hung der Genitalkammern beim Amphioxus.' Anatomischer Anzeiger, 



vii. 1892. 

 Hatschek, B. : ' Studien iiber Entwicklung des Amphioxus.' Arbeiten aus 



dem Zoologischen Institute der Universitat Wien, iv. 1881. 



'Ueber den Schichtenbau von Amphioxus.' Anatomischer Anzeiger, 



iii. 1888. 



' Die Metamerie des Amphioxus und des Ammoccetes.' Verhand- 



lungen der Anatomischen Gesellschaft, 1892. 

 Kowalevsky, A. : ' Entwickelungsgeschichte des Amphioxus lanceolatus.' 



Memoires de l'Academie Imperiale des Sciences de Saint-Petersbourg, 



vii e serie, tome xi. No. 4. 1867. 



1 Weitere Studien iiber die Entwicklungsgeschichte des Amphioxus 



lanceolatus, nebst einem Beitrage zur Homologie des Nervensystems 



der Wurmer und Wirbelthiere.' Archiv fur mikroskopische Anatomie, 



xiii. 1876. 

 Lankester, E. Kay : ' Contributions to the Knowledge of Amphioxus lanceo- 

 latus.' Quarterly Journal of Microscopical Science, New Series, xxix. 



1889. 

 Lankester, E. Bay, and Willey, A. : * The Development of the Atrial Chamber 



of Amphioxus.' Quarterly Journal of Microscopical Science, New 



Series, xxxi. 1890. 

 Willey, A. : ' The Later Larval Development of Amphioxus.' Quarterly Journal 



of Microscopical Science, New Series, xxxii. 1891. 

 Wilson, E. B. : ' On Multiple and Partial Development in Amphioxus.' 



Anatomischer Anzeiger, vii. 1892. 



