442 w. A. HASWELL. 
this usually extends some distance beyond the last of the 
chitinous bodies. 
From its base, which is slightly embedded in the bulb, to 
its apex the mouth-piece is enclosed in a sheath of cells (fig. 
18, ch. c.) which are continuous with those of the wall of the 
bursa, and not widely different from them in appearance. 
These are arranged in a single layer with their long axes at 
right angles to that of the mouth-piece, and each is produced 
into a narrow lamellar process, which becomes connected 
with one of the chitinous bodies. ‘hese cells have nuclei 
similar to the nuclei of the wall of the bursa, situated towards 
their outer ends, but, in the fresh condition, these are barely 
visible without the addition of acetic acid. 
In each cell, however, nearly always on the inner side of 
the nucleus, is, in most specimens, a rounded globule which, 
on account of its high refractive power, is very much brighter 
and more conspicuous than the nucleus itself. Like the cells 
themselves these globules gradually diminish in size towards 
the fine extremity of the mouth-piece. Hach of them is of 
about the same volume as one of the chitinous bodies in its 
vicinity. It seems to me that these appearances point to the 
conclusion that the cellular sheath of the mouth-piece is com- 
posed of cells by whose action the chitinous matter is formed, 
and that the globules occurring in the interior of the cells are 
actually chitinous pieces in process of formation. 
Where the canal enters the bulb from the base of the 
mouth-piece it becomes dilated, as already mentioned, into a 
rounded cavity (fig. 17, d’) in the substance of the bulb.t| In 
the interior of this are a number of crescent-shaped bodies, 
‘008 mm. in length, narrower at one end than at the other, 
apparently composed of the same material as the parts of the 
mouth-piece. In sections these appear irregularly arranged, 
but in their natural relations they are, in all probability, disposed 
in a regular way around the lumen with their concavities in- 
1 In some specimens a second enlargement, presenting very similar 
appearances, occurs further back. 
