LOXOSOMA LO.XALINA AND LOXOSOMA SALTANS. 133 
I have seen no trace of any duct in connection with the 
body pair. In connection with the lophophore organs there 
is a trace of a duct (vide figs. 5 and 7, k. d.), but I cannot follow 
this tube either to the exterior, though it runs close to the 
surface of the epistome, nor to the cells themselves, although, 
as seen in the figures, it lies close against them. Prouho 
found a duct which was ciliated and open to the exterior, aud 
Nickerson a similar one, but was doubtful about the ciliatiou. 
I feel pretty sure there is no ciliated duct. It is quite possible 
that the above-mentioned tube is a duct to the surface in con- 
nection with the lophophoral kidney, and that the much larger 
open space lined by irregular cells mentioned above as lying 
to the outside of the body-kidneys may be the duct of the 
body-kidney, but I cannot say whether it opens to the exterior 
or not. 
'I’he walls of the rectum in all probability ai’e an important 
part of the excretory system. Figs. 20, 21 and 24 show how 
clearly certain cells of the side walls take up the methylene- 
blue, even more distinctly than the lophophoral and body 
“ kidneys.” In the normal condition the side walls of the 
rectum are yellow like the walls of the liver diverticula of the 
gut. In each case the colour is due to spherical bodies within 
tlie cells of varying tint, but whereas the liver-cells or inclu- 
sions are hardly affected by the methylene-blue, the rectal ones 
stain deeply. 
In sections of the rectum one sees more clearly what the 
process probably is. Fig. 24 represents a section of the 
rectum taken transversely and stained with thionin, eosin and 
orange G. The cells forming the anterior aud posterior walls 
are ciliated and do not form excretory granules like the side- 
wall cells, which are larger and non-cilitated. In these there 
are large vacuoles containing masses of granules, some of 
which take the thionin, others the orange stain. These grains 
are seen to be forming in the deeper parts of the cells (fig. 
24, tx. (jr.) and passing into the vacuoles. Some of the 
vacuoles {vac.) are deep down, others {vac.') are closer to 
the surface, and some I have found at the surface. It is 
