ANATOMY OF THE EARTHWORM. 9 
off few branches and enlarging at intervals into very remark- 
able sacculi, closely connected with the tissue of the ciliated 
canal. The fluid contained in the blood-vessels is of a pale red 
colour, and in the sacculi appears to contain granular matter. 
The cilia of the canal retain their vibratile movement for a 
considerable period of time after their removal from the worm, 
and a careful examination shows that they are urging a liquid 
containing minute cells, granules, &c., towards the external 
aperture, which, it should be stated, is so minute as to escape 
detection on the surface of the worm’s body. 
It can hardly be doubted that the function of these tubes is 
excretory, and not respiratory, as sometimes supposed; and, 
indeed, this appears now to be conceded by many distinguished 
anatomists. The glandular walls connected with the sacculi 
of capillary vessels present all the essential parts of a kidney, 
and it is as such that they must be considered. The “ ciliated 
inductor’? undoubtedly removes a certain quantity of the 
perivisceral fluid from the body, but by so doing it assuredly 
does not assist the oxygenation of the red fluid, which may be 
called the blood. Tor the views which have been entertained 
on this subject, I must refer the reader elsewhere, to such 
papers as that of Gegenbaur, of Willams, and the researches 
of D’Udekem and Claparéde. Drawing a conclusion merely 
from structural grounds, the ciated canals of the Oligo- 
cheta, and hence of all Annelida, can only be considered as 
primarily excretory organs or kidneys; the facts which will 
be hereafter detailed with regard to the differentiation of 
these canals, adding also a certain amount of weight to the 
structural argument. The ciliated canais, therefore, of the 
earthworm, may be considered as znversions of the integument, 
similar in function and essential points of structure to the 
kidneys of higher animals. Inthe Lumbricus, a pair of canals 
of similar structure exists in every segment of the body but 
the first. In the Naiide, the beautiful and elaborate researches 
of D’Udekem and Claparéde have shown that in the genera- 
tive segments of the body they are modified so as to form 
“vasa deferentia’? and “Fallopian tubes.” Whether this 
arrangement obtains in any manner in Lumbricus remains to 
be considered. 
Mucous pores.—In the cuticle of the earthworm a system 
of very minute canals exists, which was briefly referred to 
in treating of the tegumentary system, and which might either 
be described in connection with the respiratory mechanism, or 
here, if we regard these ducts as excretory pores. Fig. 8, 
Pl. IT, shows a vertical section of the integument of Luméricus, 
taken from the posterior part of the body, where the colouring 
