12 E. RAY LANKESTER, ON THE 
termination and the ciliated tube bring forcibly to mind the 
ciliated tubes devoted to excretory purposes; but as these 
also exist in the same segments as the vasa deferentia, we 
are apparently prevented from considering the latter as 
modifications of the former, though we have no such difficulty 
in the case of the Limicole. The structure of the expanded 
“ ciliated inductors” of the vasa deferentia is merely a pave- 
ment of polygonal cells, excessively delicate, and most easily 
ruptured and destroyed. The continuation of this epithelial 
membrane into the duct, and the continuity of the fibrous 
sheath of the seminal vesicle, and the structureless membrane 
forming the external envelope of the duct, are seen in fig. 12, 
Pl. II. Their presence, as that of the vasa deferentia them- 
selves, appears to have escaped all observers previous to M. 
D’ Udekem, and also one since, Dr. Williams. 
The Ovaries.—The discovery of the ovaries of the earth- 
worm is also due to M. D’Udekem; they have since been 
described by Hering, and may be found, by a careful exami- 
nation of the thirteenth segment of the worm, situated on 
the inner ventral surface, close to the nervous chord (fig. 1, 
Pl.I, fig. 8, Pl. 11). This, however, becomes almost an impos- 
sibility without the use of spirits of wime, by which these 
otherwise transparent and very minute bodies are coagulated, 
and rendered visible. There is no difficulty, when their nature 
is considered, in understanding how the presence of these 
organs has been overlooked, and others mistaken for them. 
The ovaries of Lumbricus are never more than ~.th of an 
inch in length, and consist of a very fine structureless mem- 
brane in the form of a conical taperimg sac, provided with 
minute blood-vessels and enclosing ova in all stages of deve- 
lopment, those situated in the narrow part being the most 
advanced. By one extremity the ovary is attached to the 
diaphragm between the twelfth and thirteenth compart- 
ments, the other is free and tapering, being sometimes 
terminated by minute papille (fig. 3, Pl. IT), the function of 
which is indeterminable. The relative size of the ovaries 
in Lumbricus is a remarkable fact, when we consider the 
size which these bodies attain in Tubifex, Huaxes, and 
other Limicole. Dr. Williams denies the existence of these 
bodies, and asserts that both Hering and D’Udekem have 
described what they did not see. It is hardly necessary for 
me again most emphatically to confirm those authors’ state- 
ments, and to deny the truth of Dr. Williams’s allegations. 
The Oviducts.—These were discovered by Dr. Hering, and 
form a most valuable addition to our knowledge of the 
anatomy of the earthworm, inasmuch as they throw great 
