94) Frcceedivgs of the Roycd Society of Victoria. 



The digestive epithelium has been admirably described by 

 Professor von Graff in the case of Geoiiemertes chalicho- 

 phova, and aptly compared to that of the Planarians. His 

 i-emarks apply equally well to our species. Only in a 

 condition of rest or hunger are the digestive cells clearly 

 recognisable, when they have the form of elongated, 

 columnar cells, apparently not ciliated. When digestion 

 takes place these cells elongate, ])ut out amoeboid processes, 

 seize Jiold of the food particles and run together into 

 a protoplasmic network which may finally completely 

 obliterate the lumen of the alimentary canal, which then 

 appears to be filled with a granular vacuolated mass of proto- 

 plasm (syncytium). The digested food material is then, 

 api)arently, passed out to the surrounding tissues, after 

 which the digestive cells regain their normal condition, or, 

 as seems to me possible, are replaced by new ones.* 



Digestion seems to go on chiefi^^ in the lateral diverticula, 

 which gener-alh' appear in sections to be more or less filled 

 with a granular syncytium as shown in Fig. 8. In crushed 

 preparations of the living animal this gi-anular matei'ial is 

 very obvious in the lateral diverticula and can be easily 

 squeezed out into the central portion of the gut and thence 

 through the anus. 



d. The Proboscis Sheath and Frohoscis. 



The prul)oscis and its sheath have essentially the same 

 structuie as in other Hoplonemertines and a brief desciiption 

 of these parts will therefore sufiice. The sheath (Figs. G, 7, 8, 

 j). s.) is a hollow tube running along in the dorsal region of 

 the body above the alimentar}- canal, and extending from its 

 opening at the anterior extremity to its blind end very near 

 the jjosterior extrenjity. It has well-develo])ed muscular 

 walls lined internally by a layer of ei)ithelium. 'J'he 

 thickness of the nmscular part of the wall, as also that of 

 the epithelial layer, varies much according to the state of 

 distention of the sheath. When the proboscis is completely 

 retracted the walls of the sheath are necessarily much 

 distended and appear relatively thin, while when the 

 |)roboscis is everted the lumen of the sheath becomes much 

 narrower and its walls much thicker. Tlie muscular portion 



* Compare my account of the digestive epithelium in Geoplana spenceri 

 (loc. cit.) which was written before I had seen von Graft's remarks on the 

 ul jet. 



