On the struotiiie of tlio iippliriili.i of Siicliostommn. 260 



The bulb consists of 1) a cuticular structure, having somewhat the 

 form of a sphere flattened in one direction, to which may be applied 

 the designation "cuticular almond"; and 2) of a closed mantle of cells 

 enveloi)ing the former. Tlie number of these cells (C) surrounding 

 each bulb is certainly not more than ten, though I have been unable 

 to determine their exact number, owing to the difficulty experienced 

 in counting them on consecutive sections. They are membraneless, 

 as BÜRGER ('92) found the "Kölbchenzellen" of other Nemerteans to 

 be; and I agree with this investigator in attributing the absence of 

 cell-membranes to the probable function of the cells, in absorbing 

 liquids from the surrounding tissues. Their cytoplasm is so finely- 

 granulated in appearance, as to appear homogeneous with all except 

 the highest powers of magnification. The nucleus is usually oval, of 

 smaller size than those of the main nephridial ducts, and contains a 

 few chromatic granules. On a thin section (3 /n) of a bulb, only one 

 or two, seldom more, nuclei will be found on its periphery, since 

 though the cells themselves base upon one another, their respective 

 nuclei are separated by considerable distances. From these membrane- 

 less cells irregular, branching fibres are given off, which penetrate 

 into the surrounding body tissues (musculature, cephalic gland, body- 

 cavity). 



The shape of the cuticular almond, around which these cells are 

 radially grouped, resembles the hollow shell of an almond, the wall 

 or shell of which, however, is relatively much thicker than is the 

 case in this nut. This hollow cuticular structure being flattened in 

 one direction, when seen from the edge presents the appearance of 

 a narrow ellipse (Fig. 3 LO0); but when viewed from the broad side 

 (Figs. 2, 4, 6, 7) is pretty regularly oval in outline. Fig. 1 shows 

 the almond seen from the surface, while the others already referred 

 to represent sections. When studied in the fresh state, this almond 

 is refractive, non-transparent, and of a yellowish-green color; in the 

 living worm, indeed, it presents much the same ap])earance as one of 

 the larger gland-cells of the body epithelium, from which it may always 

 be distinguished, however, by its position within the cutis. Its sub- 

 stance is dense though not Ijrittle, perfectly homogeneous, and stains 

 with methylene blue (post mortem staining), but especially deeply 

 with Delafield's haematoxylin ; the usual reagents exert no influence 

 upon its texture. I have given the term cuticular to these structures, 

 since there can be no doubt that it is a cuticular formation of the 

 cells of the terminal bulb, since these cells form a closed mantle 



Zool. Jahrb. X Abth. f. Morph. 1 S 



