22 Dr. Asajiro Oka: 



It is perfectly smooth both externally and internally, and no folds 

 or thickenings, such as are frequently met with in other compound 

 ascidians, are to be seen. The stomach is nowhere ciliated. 



The intestine begins at the posterior end of the stomach, runs 

 backwards for a short distance, then turns to left and runs for- 

 wards till it reaches the bottom of the branchial sac; here it is 

 curved either to right or to left and opens into the longitudinal 

 furrow^ separating the double rows of zooids. xV short tract of the 

 intestine lying immediately behind the stomach and clearly 

 bounded by a costriction posteriorly differs from the rest of the 

 canal in many respects, and may, for the sake of convenience, be 

 distinguished as "duodenum." It corresponds exactly to the 

 " post-estomac " of some French authors and the " Mitteldarm " 

 of German writers. The remaining portion of the canal exhibits 

 nearly the same character throughout, though it may conveniently 

 be divided into three regions in referrence to the area occupied by 

 the intestinal gland. 



The duodenal part of intestine has the shape of a truncated 

 cone attached by the broad base to the posterior end of the 

 stomach. The wall, which is generally a httle wrinkled, is lined 

 with a layer of cubical cells without cilia and stains very deeply 

 with haemalaun. The alimentary canal has thinnest wall in this 

 part, and, as the stomach lying immediately in front of it is the 

 thickest walled part of the canal, the contrast in thickness of the 

 Avails is very striking. 



The intestine, exclusive of the duodenum, may be divided 

 into three regions of nearly equal length. The first third lying 

 next the duodenum occupies the hindmost region of the abdomen 

 and is bent somewhat in the form of the letter U. Next comes 

 the middle third which is distinguished by the presence of the fine 

 tubular intestinal gland covering the outer surface of the wall. 

 The last third, which may be called the rectum, is simply tubular 

 in form and opens by the anal aperture into the common peribran- 

 chial space. In microscopical structure of the wall, however, 

 there is no noticeable difference between these parts. The course 

 of the rectum is a little different according to the position of the 



