PEDAL LACERATION IN ACTINIANS. IOI 



6. The tissues of the most actively growing part of a laceration 

 piece become very thin ; the ectoderm and the entoderm lose all 

 apparent cell boundaries; the mesoglea arises as a direct continu- 

 ation of that present in the older tissues. 



7. The newly formed tissues contain a very small number of 

 gland cells and nematocysts. These two types of cells are de- 

 veloped to the usual number after the tissue relations have be- 

 become stable. 



BIOLOGICAL LABORATORY, 

 PRINCETON UNIVERSITY. 



BIBLIOGRAPHY. 

 Andres, A. 



'82 Intorno alia Scissiparita della Attinae. Mittheilungen a. d. Zool. Sta. z. 



Neapel., Bd. III. 

 Appellof, A. 



'oo Studien iiber Actinien-Entwicklung. Bergens Museum Aarbog f. 1900. 

 Carlgren, O. 



'04 Studien iiber Regenerations und Regelationserscheinungen. i. Uber die 

 correlationen zwischen der Regulation und der Symmetrie bei den Actini- 

 arien. Svenska. Akad. Handl., Bd. 37, No. 8. 

 '09 Studien iiber Regenerations und Regulationserscheinungen. Erganzende 



Untersuchungen an Actiniarien. Ibid., Bd. 43, No. 9. 

 Child, C. M. 



'o3-'os Form Regulation in Cerianthus. Biol. Bull., vols. 5, 6, 7, 8. 

 Duerden, J. E. 



'99 The Edwardsis stage of the Actinian Lebrunia, and the Formation of the 



Gastro-co3lomic Cavity. Jour. Linn. Soc., Vol. XXVII. 

 Hazen, Anna P. 



'02 The Regeneration of an CEsophagus in the Anemone, Sagartia luciae. Arch. 



f. Entw. Mech., Bd. XIV. 



'03 Regeneration in the Anemone, Sagartia luciae. Ibid., Bd. XVI. 

 Hertwig, O. und R. 

 Die Actinien. 

 Parker, G. H. 



'97 The Mesenteries and Siphonoglyphs in Metridium marginatum M. Edw. 



Bull. Mus. Comp. Zool. Harvard, vol. 30. 

 '99 Longitudinal Fission in Metridium marginatum Milne Edwards. Bull. 



Mus. Comp. Zool. Harvard, vol. 35. 

 Torrey, H. B. 



'98 Observations on Monogenesis in Metridium. Proc. Calif. Acad. Sci., 1898. 

 Wilson, E. B. 



'82 The Development of Renilla. Philosophical Trs. Roy. Sci., 1883. 



'84 The Mesenterial Filaments of the Alcyonaria. Mitt. Zool. Sta. Neapel, 



Bd. V., 1884. 

 Wilson, H. V. 



'88 On the Development of Manicina areolata. Jour. Morph., Vol. II., No. 2, 

 1888. 



