STUDIES OX THE ECTOPARASITIC TREMA.TODES OP JAPAN. 57 



I have studied, it is very short or almost entirely wanting. Its 

 internal surface presents just the same aspect as that of the intestine, 

 and therefore will be described with that. In Monocotyle, Calicotyle, 

 and Tristomuin, (and probably also in Epibclella) numerous unicellular 

 glands open into the oesophagus at its very beginning (PL XX, fig. 

 8 ; PI. XXI, fig. 1 ; Pi. XXIV, fig. 12 ; PL XXV, fig. 7 ; PL 

 XXIII, fig. 4 ; PL XVIII, fig. 5 ; PL XIX, fig. 8), which have 

 been called the salivary glands. In Monocotyle and Calicotyle, they are 

 situated close around the oesophagus, and in the former also a little 

 behind it (PL XVIII, fig. 5 ; PL XIX, fig. 8). In Tristomwri, how- 

 ever, they are situated quite in the lateral portion of the body on the 

 dorsal side, and are connected with the oesophagus by long ducts (PL 

 XX, fig. 8). The cells present somewhat different aspects (PL 

 XX, fig. 9 ; PL XVIII, fig. 5) ; they stain well, but in some the 

 cell-body is comparatively finely granular, and the oval, vesicular 

 nucleus encloses in its centre a single, well staining nucleolus, while 

 in others the cell-body is more coarsely granular and the large, round, 

 vesicular nucleus usually encloses a few small nucleoli besides the 

 large one, all of which stain more weakly than in the first class 

 of cells. Cells of the first class also stain more deeply than those 

 of the second. These differences are no doubt due to the different 

 stages of secretory activity ; for, intermediate forms of all degrees 

 are also present. 



In Tristomum, the oesophagus is separated from the intestine 

 by valve-lilie projections of the surrounding tissue into the cavity 

 of the alimentary canal in which sphincter muscular fibres are 

 present. (PL XXI, fig. 1 ; PL XXIV, fig. 12 j PL XXV, fig. 7 ; 

 PL XXIII, fig. 4). 



In Microcotyle, Axine, OctocotyUj, DlcUdopliom, Hexacotyle, and 

 Onchocotyle, the salivary glands are absent. 



