MONILIGASTER GRANDIS, A.G.B. 339 
with a chromo-osmo-acetic acid mixture much finer ramifica- 
tions which terminate in the periphery of cells. The limit 
between one cell and another does not show clearly, as it does 
in the case of similar cells in Hirudo. 
The walls of the large ductules of this system are here and 
there set with cilia arranged very irregularly, and there are also 
numerous undulating structures composed of bundles of long 
cilia-like filaments running along, or very obliquely across, the 
lumen (fig. 45). At each end the filaments of the bundle are 
gathered together and attached to the wall of the ductule. The 
bundles vary in length from about ;1, inch to 5,55 inch, and 
each bundle consists of some ten or twelve filaments. When 
the movement is rapid the bundle undulates as a whole, the 
wave always starting from one end—the end nearest the 
nephrostome—but as the movement becomes slacker it con- 
stantly happens that the waves start at slightly different mo- 
ments in the individual filaments, with the result that they 
separate from one another ; in fact, a wave of separation passes 
along the bundle. Except for the fact that these filaments 
are attached at both ends, they are remarkably like the tufts 
of fine vibratile cilia which constitute the so-called “flame” 
of the excretory canals of the Platodes. I have made a very 
careful study of these structures, and am quite convinced of 
the accuracy of the above statements. ‘They are quite clear 
in some of my chromo-osmo-acetic acid preparations, and on 
one occasion I watched them in a fresh preparation on and off 
for nine hours as the movement became gradually slower and 
slower. ae 
The walls of the narrow duct are very like those of the nar- 
row duct of Lumbricus in structure. I have never been 
able to quite satisfy myself that the branching tubules collect 
into one limb of the narrow duct only, as shown in fig. 42 at 
6, but I think that they do, and that the transverse tubules 
joining the two limbs of the narrow duct are secondary forma- 
tions. I have not found cilia in any part of this narrow tube. 
The walls of the middle tube are much thicker, and they pre- 
sent a striation similar to that which I described as existing 
VoL. 36, PART 3.—NEW SER. AUK 
