338 ALFRED GIBBS BOURNE. 
piece only of the spirally-twisted portion of the glandular lobe, 
diagrammatically shown in the apical position). Where the 
narrow tube ends (d) what may be called the middle tube 
commences; this (‘‘de,” “ef,” and “‘fg”’) runs back along the 
whole length of the glandular lobe to the apex, and then returns 
upon itself and passes on to the proximal extremity of the 
glandular lobe (g), close to the spot where the latter was joined 
by the nephrostomial duct. The middle tube is followed by the 
wide tube (the vesicle duct, marked ‘gh’’) which enters the 
vesicle (at the point marked h). The shape of the vesicle 
is shown in the figure; there is a sphincter muscle (7) at the 
spot where the terminal duct is given off. The terminal duct 
is a wide duct, and is much longer in some of the nephridia 
(e. g. those of Segment x1) than in others. 
The nephrostome is very like that of Lumbricus. Ihave . 
studied a very large number of these organs and have counted 
between forty and fifty marginal cells, and have satisfied my- 
self as to the existence of one or perhaps two central cells (in 
fig. 42 I have drawn one nucleus of such a cell, but in one 
preparation [fig. 43] at any rate there were two similar nuclei 
side by side). I have been unable to ascertain anything clearly 
with regard to ‘ gutter ” cells. 
The nephrostomial duct penetrates the septum at a spot 
somewhat removed from the body-wall and opposite the inner 
seta rows. The nephrostome is about ;4,; inch across at the 
widest part. 
The nephrostomial duct has very thin walls, richly ciliated 
(I do not think that the cilia are arranged in spiral lines, there 
is no appearance of such an arrangement) and covered with 
connective tissue in which there is a little pigment, rendering 
the duct rather easy to follow. 
In the branching system of ductules the lumen is always 
- very irregular; it can be well seen in quite fresh prepara- 
tions, the finer ramifications show only when distended with 
fluid. Fig. 46 accurately represents the appearance obtained 
by focussing just below the surface of a portion of this region 
of the glandular lobe, but I have seen in preparations treated 
