STUDIES Oy THE ECTOPARASITIC TEEMATODES OF JAPAX. 55 



There is another peculiarity in the pharynx of M. reticulata, and 

 that is that its anterior end is prolonged into a tube with pointed end 

 and with a thick wall which is differentiated into two layers unstained 

 by borax-carmin, the outer of which is very refractive. Both these 

 laj'ers are homogeneous and without structure. 



In all the species of Tristomiim that I have; studied, there are 

 numerous papillae on the surface of the cavity of the anterior half of 

 the pharynx ; and in some species, as in Tr. ovale (PI. XXIII, fig. 4) 

 and Tr. sinuatum (PI. XXI, fig, 1), these papillae are present also at 

 the anterior margin. They mark the openings of numerous unicell- 

 ular glands, which have been called " Kornerdriisen " or " Pharyn- 

 gealdrlisen " by Max Braun.'^ I shall adopt the latter name and 

 call them pharyngeal glands. The glandular cells themselves are 

 situated, so far as I have observed, not as praun states, in the wall 

 of the pharynx, but outside it, that is, in the mesenchyma of the 

 median portion of the body behind the pharynx, as may be 

 clearly seen in fig. 5, PI. XXI, which represents a horizontal 

 section of the region in question in Tr. simtatwn. They are very 

 numerous, and vary in form from a typical goblet to a more or less 

 oval or polygonal shape. The goblet-shaped cells, the comparatively 

 large efferent ducts of which can be generally traced very distinctly to 

 the wall of the phai'ynx, have vesicular nuclei each with one or 

 more, faintly stained nucleoli ; both the cell-body and the efferent 

 duct are entirely filled with coarse granules which stain but slightly 

 with haematoxylin. On . the other hand, those which are oval or 

 more or less polygonal in form have each a rather small nucleus with 

 a single, deeply staining nucleolus ; and the cell-body is very finely 

 granular and deeply stained (PI, XXI, fig. 5). Both these and the 

 goblet-shaped cells seem to be entirely destitute of a membrane, 



1). Braun — " Wiirmer " in Bronn's Klassen u. Ordnungen. p. 450. 



