556 T. iKEPA : 



Thus it will be seen that while some authors have apjxirently 

 confounded the organ with the overlyins: corpuscle masses, others 

 have considered it to ])e a glandular appendage of the stomach, 

 and still others have regarded it as a skeletal structure. Accord- 

 ing to Mastermax, who maintains the last mentioned opinion, the 

 stomach wall is produced, in the antero-lateral region, " into two 

 remarkal)le diverticula which in the fully developed larva lie as 

 a pair of elongated organs, Notochords, laterally to the oesophagus " 

 ('97, /.<?., p. 302). The organs are said to soon undergo a remark- 

 able metamorj^hosis, i.e., vacuolization. The vacuoles are produced 

 successively one after another at the distal ends of the cells and 

 are arranged alternately in several layers. On account of these 

 facts Masteeman rejects the view that the organ is of a glandular 

 nature, and holds that it is to Ijc compared in function and structure 

 with the notochord of the Chordata. In 1898 Roule published 

 his third paper on Äct'inoirorha, in which he denied that the organ 

 is double in number and lateral in position to the œsophagus, 

 but admitted the vacuolization in the larva of Phoronis sabatieri 

 {~P. 2)-^''fmwopkiIa CoEi). 



I can not at present decide wdiether the variations in the 

 mnnber of the diverticulum and in the deoTce of vacuolization are 

 of s2:)ecific value or not. For the present I must be content with 

 simj^ly noting that the stomach diverticulum in the larva^ studied 

 by me is constantly unpaired and undergoes no farther vacuolization 

 process than the production of one vacuole in each celh 



Intestine. The intestine which leads to the anus is a slender 

 canal whose wall is composed of a layer of somewhat cylindrical, 

 ciliated cells with round nuclei (figs. 4.") and 48, iniÀ. 



