VERMES, CCELENTERA AXD PROTOZOA. 173 



or manubrium. The results obtained by Claus are in 

 accordance with those of Playfair McMurrich, 1 who, work- 

 ing quite independently of the German professor, dis- 

 covered no trace in the development of Cyansea arctica 

 of an ectodermic stomodaeal invagination. 



Since the publication of the results obtained by Claus 

 and McMurrich, Prof. Goette of Strasburg has again 

 entered the field, and in the description he gives of the 

 development of Cotylorhiza and Pelagia confirms his 

 previous statements as to the existence of an ectodermic 

 stomodseum in the Scyphomedusae. 2 Without reference 

 to or comment upon the results obtained by Claus and 

 McMurrich, Prof. Goette describes the formation of an 

 ectodermic stomodseum and an oesophageal perforation 

 or " Schlundpforte " connecting the stomodseum with the 

 ccelenteron. He goes further than this, however, and de- 

 clares that the second pair of gastral pouches and all its 

 derivates are also formed by the ectoderm. The gonads 

 and gastral filaments of the adult medusae may, however, 

 occur in all the pouches ; consequently some of them must 

 be of ectodermic and others of endodermic origin, a con- 

 clusion which would entirely upset the importance of the 

 place of origin of the sexual cells of Ccelenterates, as insisted 

 upon by the Hertwigs and others. 



It is not likely that Goette's views on this important 

 point will meet with any very general acceptance until 

 his results have been completely confirmed by indepen- 

 dent observers. It is an extremely difficult matter in 

 studying the development of many forms of Ccelenterates 

 to determine with any degree of certainty where the ec- 

 toderm cells end and the endoderm cells begin. There 

 is very seldom any abrupt limit between the two germinal 

 layers at the points where they meet, and, as Goette him- 

 self admits, in the Scyphomedusse the layers are connected 



1 McMurrich, J. P., The Development of Cyanaea arctica, Am. Nat., 

 1 89 1. 



2 Goette, A., Vergleichende Entwicklungsgeschichte von Pelagia nocti- 

 luca, Z. f. zviss. Z00L, lv., p. 645. 



