Haswent—A Monograph of the Temnocephalee. 107 
opening. There is no line of demarcation between these sets of cells, nor are the 
eroups distinguishable except by tracing out the course followed by the ducts, the 
several sets being more or less intermingled. 
In each of the cells of the first two sets there are developed innumerable minute 
rod-like bodies 0075 mm. in length* (in 7. fasczata), sometimes straight, usually 
slightly curved, and usually slightly dilated at the ends. These rods pass out through 
the duct, which runs forwards, forming, along with the ducts of neighbouring cells, a 
tolerably thick strand passing towards the bases of the tentacles, the individual ducts 
branching and anastomosing. In front there is usually a shght dilatation of the 
strand (vzde Pl. xv. fig. 1, ~ ad.) which would seem to indicate the presence of a 
dilatation of the constituent ducts, apparently to form small reservoirs for the 
secretion, From this poimt some of the ducts pass to the integument behind the 
bases of the tentacles ; most of them pass along the axes of the tentacles, ramifying 
and anastomosing as they go. Finally the terminal branches open on the exterior 
through the pore-canals all over the ventral surface of the tentacles and the integu- 
ment of the body some distance behind the bases of the latter. 
Through this system of ducts the rod-like bodies pass forwards, moved, appa- 
rently, by the general contractions of the muscles of the body-wall and parenchyma, 
and they are usually found packing the interior of the branching channels in the 
tentacles. From these they pass out, one by one, through the pore-canals, accon- 
panied by a glutinous fluid. It is this secretion containing these rod-like bodies that 
would appear to give the tentacles their adhesive power when laid flat on a smooth 
surface. When the tentacles are separated from the surface of a glass slip on which 
the animal has been placed, the surface of the glass retains adhering to it a large 
number of the rods with a layer of the viscid fluid in which they are embedded. 
Like the corresponding secretion in the Rhabdoceeles, as held by y. Kennel, + 
Boéhmig,{ and others, this secretion probably aids in the capture of struggling prey 
by clogging and hampering their movements. 
Behind these tentacular glands are the acetabular glands, the secretion of which 
reaches the exterior on the inner surface of the sucker. Usually these are situated 
far back near the base of the sucker. In essentials they resemble the tentacular 
glands, and their secretion is of a similar character ; its function appears to be to add 
to the adhesive power of the sucker. 
* The length is given as ‘02 mm. in my former paper ; this is an error, since it would make the rods about a fourth 
of the diameter of the whole cell. 
+ ‘* Untersuchungen an neuen Turbellarien.” ‘ Zool. Jahrbiicher,’ 1889. 
+ Loc. cit. 
