116 Macieay Menmoriat Vouume. 
near the dorsal surface beneath the layers of muscle ; many of the terminal branches 
enter the protoplasm of the large excretory cells to be presently described. They 
contain “ Wimperflammen” in some parts at least,* but whether in the general 
course of the capillaries or in special dilatations has not been determined. Certain of 
the branches, however, have a very special mode of ending now to be described. 
There enter the substance of the wall of each excretory sac (PI. x. fig. 12) on 
the inner side a number of small canals which come off from the anterior main trunk. 
These branch through the protoplasmic substance of the wall of the sac, giving origin 
to a rich plexus of exceedingly fine capillary canals (about 004mm. in diameter), 
which do not appear to have any special walls. In the course of these capillaries 
and in slight terminal dilatations of side-branches are numerous “ Wimperflammen ” 
‘005mm. in length. The latter are at all times difficult to see: the animal must be 
pretty strongly compressed in order to bring them into view, and after a few ininutes 
of such compression their movements cease, and they are no longer to be distinguished. 
In many cases I have failed to see them altogether ; in others only one or two came 
into view ; only in a few rare instances have I succeeded in seeing a number of them 
in motion all at once, with that peculiar restricted undulating movement which once 
seen cannot be mistaken. In one case in 7. Dendyz as many as twenty were seen in 
movement at once, and there are probably many more in each sac. In 7. Move- 
zealandi@ they are still more numerous—about fifty being sometimes visible at once. 
In this species it was noticed that when the terminal sac was distended the flames in 
its walls did not appear to move. The general arrangement of these capillaries in 
the wall of the sac as seen in 7. Dendyz is represented in fig. 12 of Plate x. In 
T. minor and T. Nove-zealandie the arrangement is similar. 
In sections of specimens prepared by Flemming’s method and stained with alum- 
cochineal or hematoxylin this remarkable system of intracellular capillaries is readily 
traceable (Pl. x. figs. 13, 14 and 15), though it is a little difficult to be sure of the 
“ Wimperflammen,” which are always, as is generally recognised, difficult to make 
out—if at all recognisable—in sections.t 
Other branches end in the substance of certain peculiar cells which may be called 
the excretory cells. The branches in question are sometimes of large size as compared 
with those that enter the substance of the wall of the terminal sac, with a compara- 
tively thick protoplasmic wall, but in other cases are exceedingly fine capillaries. 
The exeretory cells are very large—as much as ‘15mm. in diameter. Each has a 
*T have found them in the tentacles, immediately in front of the brain, at the side of the excretory sac, a little 
distance in front of it, and in the neighbourhood of the ovary and receptaculum vitelli. Where flames were detected, no 
nuclei were ever observed in close proximity to them. 
+ The ‘‘ vacuoles” in the protoplasmic wall of the terminal sac referred to by me in my earlier paper are really the 
larger of these canals, or rounded spaces which the latter give rise to when the sac becomes altered by too great compres- 
sion or by the action of acids. 
