6 Dr. R. Greeff on the Annelid Genus Spherodorum, 
phery, corresponding with the narrowest border of the orifice, 
breaks through, and the two ends then separate from each 
other; so that instead of the round hole in the nuclear sub- 
stance we have a deep indentation of the nuclear substance 
penetrating from the circumference towards the middle. By 
this simple process therefore, as may be readily seen, the form 
of the above-mentioned glandular tube is very soon produced : 
at first, by the two ends becoming rounded, it has nearly the 
appearance of a sausage with two surfaces in apposition; and it 
frequently retains this form even in the fully developed state. 
But generally, during the further growth of the tube, its two 
extremities separate more or less, and then one of them becomes 
bent or rolled up, so as even to embrace the neighbouring 
tubes; and thus the position and form of the individual glands 
is altered in many ways, and the above-described appearance of 
the vermiform, tortuous, glandular coil as the contents of the 
capsule is produced. 
As regards the further histological differentiation of the indi- 
vidual glandular tubes, these, during the processes just de- 
scribed, become more and more filled with darkly granular 
substance, in which afterwards larger pale bodies make their 
appearance; these gradually increase, until finally the whole 
tube is filled with the roundish corpuscles, or, as KGlliker calls 
them, cell-like structures, above described. The perfectly formed 
glandular tube is attached by one end, or frequently, as it seemed 
to me, by both ends, to the wall of the capsule; but only one 
extremity, and with it the wall of the capsule at the same spot, 
exhibits a roundish external orifice. 
The number of glands enclosed in a capsule is not constant. 
The above-mentioned large capsules standing in regular trans- 
verse rows generally contain three or four, rarely more (figs. 10 
to 14); the smaller only one, or, at the utmost, two tubes. 
On various parts of the surface of the body, partly upon and 
partly between the vesicles, and sometimes even within them, 
we frequently see dark-brown marks (plaques), forming the most 
multifarious figures, which are often, in consequence of their 
tenacious consistence, much elongated, and only connected by 
narrow bridges. These substances appear to have nothing to do 
with the pigment-structures which so frequently occur in the 
skin of Annelids; but whether they are, as I suppose, to be 
regarded as the secretion furnished by the glands, and what 
purpose is served by it in this case, 1 cannot decide. 
I have already called attention to the gradual transition from 
the small clavate cutaneous structures, resembling the tentacles 
which stand upon the anterior portion of the head, to the globular 
ones which succeed them, and indicated that a change of func 
