GASTRODES rARASITICUM KOROTNFFl'. 8i 



vascular system is more or less simplified, as mentioned already. 



Of the epithelium constructing the wall of the gastro-vascular 

 system, one can distinguish two sorts, which may be called the ciliated 

 and the vacuolated epithelium respectively. The former (PI. 9, fig. 6; 

 c/i) is low and resembles somewhat the ventral epidermis. It shows 

 vesicular nulei at rather regular intervals. But I could not find ciliated 

 rosettes in that epithelium nor in any other part of the body. The 

 latter kind of epithelium, on the other hand, is more or less thickened 

 and contains vacuoles and food material. Of the food material, the one 

 depicted in PI. 9, fig. 2, / is most commonly met with. It is an 

 aggregate of granular bodies which take acid dyes weakly and contain 

 a small and highly basophilous nucleus. This is surely what Korotneff 

 ('91) has called ' Plasmahaufen '. Evidently they are nothing more 

 than the blood-corpuscles of Sal/>a taken into the cells. The detritus 

 matter or undigested part of food material is expelled into the lumen of 

 the canal together with a small amount of the surrouding cytoplasm and 

 forms corpuscles that rotate along with water through the canal-system, 

 just in the same way as Abbott has described in Coeloplana ('02, '07). 

 In living individuals the rotation of such corpuscles offers a striking 

 spectacle just as in Coeloplana. PI. 9, fig. 5 shows one of such corpuscles 

 just about to be formed and another already formed and lying in the 

 canal lumen. The corpuscles often contain a nucleus which sometimes 

 exhibits clear signs of degeneration. 



The distribution of the two kinds of epithelium in the canal-system 

 resembles much that in ordinary ctenophores. In the meridional and 

 tentacular canals, the external side is lined by the vacuolated epithelium, 

 whereas the internal side is clothed with the ciliated (PL 8, figs. 11-14). 

 In the tentacular canal, the wall on the external side is thickend very 

 much and contains quite a large quantity of food material. The wall 

 of the pharyngeal canal is made up of the vacuolated epithelium on the 

 lateral sides and of the ciliated one on the external and internal sides 

 (fig- 13' pJ^- '^)- The excretory canals are lined with the ciliated 

 epithelium of the same character as that of the infundibular wall. 



Gonad. 



It is a rather striking fact that all of the individuals of Gastrodes 

 examined, notwithstanding their small sizes, contained very large 

 egg-cells. But, in spite of this fact, none of the individuals showed 



