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[Vol. XV. 
surface of the latter, these ducts transversing a large number of 
body segments (in certain of the enchytraeid Oligochaeta there 
have been described subcutical gland cells whose ducts pass 
through a number of segments, but I believe that they are not 
of the same relative length as those of Piscicola). Each cell has 
its own duct, the latter being morphologically merely a process 
of the cell (Figs. 178, 181, 202); and as these individual ducts 
run in bundles parallel to one another, on their way to the sur¬ 
face of the body, they become closely apposed to one another, 
but there are apparently no open communications between the 
several ducts, nor do they unite to form larger, compound ducts. 
The ducts of those gland cells which are situated behind the 
sexual pore necessarily have an anterior direction, while those 
which are situated near to the head end of the animal send their 
ducts posteriorly. The duct departs from the cell more or less 
at right angles from its distal end, i.e., that end which is usually 
directed towards the central axis of the worm. Since the greater 
number of these cells become filled with secretion only when the 
worm is sexually mature, and since they all open on the surface 
of the body near the sexual pore, they have probably the same 
function as the clitellar glands of the Oligochaeta; after these 
observations had been completed I found that Bourne (’ 84 ) had 
described such gland cells in Pontobdella as “ clitellar glands,” 
but he made no observations on their finer structure. 
In studying the cycle of the structural changes of these 
cells two main morphological periods may be distinguished : 
(1) th z prophasis, from the immature cell to the cell filled with 
secretion ; and (2) the metaphasis , from the time when the 
cell begins to discharge its secretion until it becomes re-formed 
into a functionally immature cell again. I have no means of 
determining whether a given cell becomes filled with secretion 
only once a year (as, eg. y at the period of sexual maturity) or 
whether it may secrete several times in succession during the 
sexual period. At any rate, all appearances lead me to con¬ 
clude that it secretes periodically, most probably once during 
each period of sexual maturity. I have found no evidences that 
it secretes only once and then dies to become absorbed by 
the other tissues of the body; in other words, there were no 
