10 E, RAY LANKE&STER, ON THE 
matter is deficient. The thin structureless epidermis (a) is 
seen to be underlaid by a somewhat fibrous, but more or 
less homogeneous tissue, in which are excavated a series of 
canals of great minuteness, but sufficient to form a most 
extensive communication between the perivisceral fluid and 
the exterior. These canals branch much in the same way as 
the interstitial canals of dentinal tissue, and indeed, present 
a very marked resemblance in arrangement and form to the 
tubules of the teeth. Whether the communication of their 
contents with the surface is direct by orifices in the epidermis, 
or whether it takes place by a process of osmosis, appears to 
be uncertain. It is undoubtedly through these minute canals 
which exist throughout the integument of the earthworm, 
that water passes to the perivisceral cavity, and a denser fluid 
passes out, though it appears that the setigerous glands 
briefly noticed in my last paper, also secrete a fluid of con- 
siderable density, which is stated by Dr. Willams to have a 
remarkable power of absorbing oxygen from the atmosphere. 
This is no doubt a valuable and convenient property in 
the mucous secretion, but I have not been able to test if in 
any way, and cannot, therefore, confirm Dr. Williams’s state- 
ment. The consideration of the respiratory, vascular, and 
nervous systems of the earthworm must be deferred for 
the present, and the much-disputed organs of reproduction 
noticed. 
Oreans or Rupropuction.—It is impossible here to review 
the various errors most pardonably made by some of the 
earlier writers on this subject; Home, Movren, Dugés, and 
others, were misled by the presence of parasites, and by the 
absence of any conspicuous true ovary, into all kinds of 
mistakes. The papers of M. D’Udekem and Dr. Hering, 
whose truth and accuracy is denied by Dr. Williams, whilst 
seeking to support an untenable theory, have, however, 
made the field clear, and the discovery of the true ovaries 
due to M. D’Udekem, has rendered the appreciation of the 
vest of the “ genitalia” a comparatively easy task. 
‘Testes and Seminal Vesicle-—The testes have been de- 
seribed with considerable accuracy by Dr. Ewald Hering ;* 
but, by some means, that author has been led to regard them 
as seminal vesicles; whilst he calls certain very minute 
bodies, which they contain, the true testes. D’Udekem, on 
the contrary, regarded the seminal vesicles of Hering, as I 
also am disposed to do, as the male glandular organs. They 
consist of two pairs (Pl. A, figs. 1, 3), the anterior of 
which is bilobed, placed in the eleventh and twelfth seg- 
* ©KOll. and Siebold’s Zeitschrift,’ 1857, 
