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represent his free nuclei, although in one series of sections there were 
a few large nuclei with nucleoli lying between the layers of glands. 
I did not get the nuclei of the calceo-cutaneous glands at first, but 
made some preparations of them afterwards. Claparede’s Rinde is 
of course the radiating muscular tissue I have represented in Fig. 2 e. 
It is strange that Claparède does not figure any ducts to the 
calceo-cutaneous glands, as they are to a certain extent to be seen in 
all my sections. These ducts have at starting a diameter of about 
66u. They then taper down to 3°3 p, finally passing through the 
cuticle with a diameter of from 1°6 to 2:2 wu. TI had great difficulty in 
finding the openings of them. At first by a process of double staining, 
it was quite easy to trace them up to a certain point, even after they 
had begun to mingle with the calceo-cuticular glands. Then all signs 
of them vanished. I subsequently found, however, by other methods, 
that on approaching the surface they became granular and took the 
other stain, so resembling the ducts of the calceo-cuticular glands that 
it was all but impossible to distinguish between them (see Fig. 2). 
Although not shown in a single section, it is certain that each gland 
has a separate duct. 
The capillaries are extremely difficult to find, and I think that 
great credit is due to Claparè de for having worked them out. We 
have first of all a large vessel (which may be from 9°9 to 6:6 u thick) 
traversing the body in a circular direction on the external surface of 
that particular muscular layer which happens to be outermost. Then, 
as this goes along, it sends off radial capillaries, which, after reaching 
about the lower extremities of the calceo-cuticular glands, turn round, 
and, without anastomosing, go downwards to join the main vessel 
again—thus edging one glandular column. This condition of the ca- 
pillaries is, 1 think, of a very interesting character, and affords a good 
illustration of the variety of form which is to be met with in the capil- 
laries of the annelids. 
I have not been able to get really satisfactory preparations of the 
peripheral nerves. i 
With reference to the origin of the clitellum, whether it secretes 
the cocoon, or whether, as I suppose, it has only a copulatory func- 
tion, it is in any case necessary to consider why there should be two 
series of glands, and the work which each of them does. First of all, 
we can very readily imagine that in the primitive worm the epidermis 
consisted of simple nucleated cells, similar to the epithelial cells of the 
intestine. In fact D’Udekem (who first investigated the histology of 
the clitellum) actually compared the calceo-cutaneous glands with the 
