§$ 159. 
THE ANNELTDES, 
§ 159. 
With the Hirudinei, and Lumbricini, the peculiar canals found in the 
abdominal cavity may be regarded as internal branchiae, or as aquiferous 
vessels. 
The intimate structure of this aquiferous system is difficult to unravel 
with the Hirudinei. It is most easily observed with the Branchiobdella; here 
there are only two pairs of curved canals whose inner surface is ciliated. 
One of these pairs opens upon the ventral surface at the beginning of the sec- 
ond third of the body, while the other opens at the extremity near the median 
line. Each of these four canals is dilated just before its external opening 
into a round, yellow cavity, from which pass off many loop-like vessels.” 
With the other Hirudinei, these organs in pairs are more numerous, and 
situated one after another from the second third to the extremity of the 
body. 
Tt is remarkable that the ciliated epithelium lining these canals with Bran- 
chiobdella, is absent in all the other species.” 
The structure of the respiratory system of the Lumbricini is not less 
difficult to be understood. With all the genera there are, at the commence- 
ment and on each side of the intestine, very tortuous canals which open 
upon the ventral surface, by a narrow orifice near the median line. These 
canals are lined with long cilia which have an undulatory movement; ® 
they also are colorless and sometimes have dilatations before opening exter- 
nally, but they never contain air, so that the terms tracheae or pulmonary 
cells, have been erroneously applied.” Often they float loosely in the 
cavity of the body, and their free extremity has an orifice surrounded by 
long vibratory cilia. 
1 See Henle, in Miiller’s Arch. 1835, p. 576, 
Taf. XIV. fig. 1. “This epithelium would undoubt- 
edly favor the constant renewal of water in these 
canals. 
2 With Sanguisuga, there are seventeen pairs 
of these organs. They have been taken by Brandt 
(Med. Zool. II. p. 251, Taf. XXIX. A. fig. 55-58) 
for organs of special secretion, since he has seen a 
whitish liquid escape from their ventral orifices. 
The riband-like organ of these Amnelides is not, 
moreover, as is usually supposed, a simple canal, 
but is composed of numerous interwoven and fre- 
quently interanastomosing canals, having no trace 
of ciliated epithelium. 
From Duges’ remark (Ann. d. Sc. Nat. XV. 
1828, p. 308, Pl. VIIL. fig. 2), I think it probable 
that this, net-work is formed of blood-vessels which 
are occasionally empty, for I have always found 
them colorless. : 
In this case, the real aquiferous canals are prob- 
ably concealed in the net-work, and from their want 
of ciliated epithelium not easily seen. 
With Nephelis vulgaris, I have seen the same 
number of internal branchiae as with Sanguisuga. 
Here, the aquiferous system appears as a knot of 
* [§ 159, note 2] See, upon the circulatory sys- 
tem of Branchellion, Quatrefages (Ann. d. Sc. 
Nat. XVIII. 1852, p. 314). According to him, the 
general cavity of the body here, is represented by 
a collection of canals which are lacunae. This 
forms a vascular lymphatic system which circulates 
chyle to the branchiae ; these last are, therefore, 
“ branchies lymphatiques.” 
With some, however, they terminate by thickly- 
colorless, non-ciliated canals connecting with a 
vesicular pouch which is’ filled with red blood ; so 
that in the posterior two-thirds of the body there 
is a double row of seventeen sanguineous sinuses, 
inside the lateral vessels. These sinuses, already 
carefully described by Miller (Meckel’s Arch. 
1828, Taf. I. fig. 1), take no part in the pulsations 
of the main vessels, and are not alternately emp- 
tied and filled during the transverse circulation of 
these animals. 
A very interesting fact to me, is the existence 
with this Nephedis, of a multi-lobulate, rosetted, 
ciliated, colorless organ in the interior of these 
sanguineous sinuses.* 
8 See Henle, in Miiller’s Arch. 1837; p. 84, Taf. 
VI. fig. 7, 8, v. w (Enchytraeus) ; and Gruithui- 
sen, Nov. Act. Acad. Nat. Cur. XI, 1823, p. 238, 
Tab. XXXV. fig. 1, i., XIV. 1828, Tab. XXYV. fig. 
5 (Wats and Chaetogaster). 
4 An aqueous respiratory fluid circulates in 
these canals undoubtedly by the aid of cilia. The- 
terrestrial Lumbricini which live only in the damp 
earth obtain this fluid therefrom. 
5 I have observed this with Saenuris varie- 
gata, Lumbriculus variegatus, Nais elinguis, 
He also states‘as conclusions : 
1. The no: of the abd 
sels with the branchiae. 
2. The existence of a subcutaneous lymphatic 
vessel. 
8. The origin from this vessel of trunks which 
go to the branchiae. — Ep. 
1 ves- 
