118 THE HELMINTHES. § ITS. 
CHAPTER VIII. 
ORGANS OF SECRETION. 
§ 118. 
No orga 1s of secretion have been found, except in the Trematodes and 
Nematodes, In most of the Trematodes, there is, upon the median line of 
the posterior part of the body, a contractile sac, which usually opens out~ 
wards, at the caudal extremity, and seldom at the posterior part of the 
back.® This sac is single,” bifurcate,® or multiramose. In the last case, 
its branches are spread usually over the whole body. Its walls are quite 
thin, and therefore, it is seen with difficulty when wholly contracted or 
empty. It contains a colorless liquid filled with numerous granules or 
vesicles, which, during the contractions, pass up and down, or escape 
through the external opening. This organ is sometimes so crowded with 
clear, solid corpuscles, composed apparently of earthy matter, that exam- 
ined by reflected light, it has a cretaceous aspect.” 
In many Nematodes, there is on the ventral surface and at a variable 
distance from the head, a small oblique opening surrounded by a sphincter. 
In some species, two canals pass from it and run backwards on each side 
of the intestinal canal; and in others, there are also two other canals which 
extend forwards in the same way. The use of the colorless and homoge- 
neous secretion of these organs is yet unknown.” 
1 This opening, known as the Foramen caudale 
with Distomum, Holostomum, Monostomum, 
Aspidogaster, and Diplostomum, has formerly 
been compared to an anus by Nardo (Heusin- 
ger’s Zeitsch. fiir organische Phys. 1827, I. p. 68), 
and by Baer (Ibid. II. p. 197). Mehlis (Observ. 
de Distomate,p. 16) having shown that it belonged, 
in Distomum hepaticum, to a particular organ 
which is ramified like a vessel, has properly re- 
jected this analogy ; see Isis,1831, p.179. With 
the larvae of Trematodes, known as Cercaria, 
Bucephalus, and Distomum duplicatum, the 
base of the tail is thrust into the excretory opening 
of this organ, and its contents cannot escape until 
the animal has lost the tail. 
2 Amphistomum. 
3 Monostomum faba, Distomum cirrigerum, 
Gasterostomum jfimbriatum, and Bucephalus 
polymorphus. 
4 Distomum chilostomum, clavigerum, lima, 
maculosum, tereticolle, variegatum, and many 
species of Monostomum, — where the two closed 
ends of the sac often extend to the cephalic ex- 
tremity. With Distomum appendiculatum, the 
two branches of the excretory organ unite directly 
behind the oral sucker. With Aspidogaster con- 
chicola, it divides into two canals near the Fora- 
men caudale, which extend to the anterior ex- 
tremity. In Amphistomum, two similar canals 
wind from the head along each side of the body, to 
the middle of the posterior back, where they open 
outwards, after having formed by retinion a pyri- 
form reservoir. Laurer (De Amphistomo conico. 
p. 10, fig. 22) has given a figure of this reservoir, 
in which he has confounded the secretory canals 
with the nutritive vessels. 
3 Beside Distomum hepaticum, Holostomum 
urnigerum, the Distoma also with a spinous 
head, have a widely-ramified excretory organ ; see 
Mehlis, Isis,1831, p. 182. 
6 With the spinous-headed Distomum militare, 
and echinatum, this organ is often so reduced in 
substance, that here and there are perceived only 
isolated groups of the ramified canals. 
7 The solidity of these corpuscles may have been 
the reason why Ehrenberg (Symb. Physic. Anim. 
Evertebr. Ser. I. Phytozoa entozoa) has taken those 
of Cercaria ephemera for eggs, and the twocanals 
of the excretory organ for ovaries; and why 
Nordmann (Microgr. Beitr. Hft. 1, p. 54, Taf. I. 
fig. 7) has regarded their escape from the body 
with Distomum annuligerum, as an act of ovi- 
position, 
The corpuscles of this kind found in the excretory 
organ of certain Trematodes, as for instance in a 
larva of Monostomum known as Cercaria ephem- 
era, remind one from their aspect, of the small 
calcareous subcutaneous bodies of many Taeniae, 
and it may be asked if they are not an effete mate- 
rial, which, not being contained in proper organs, 
is with these H thus sub ly 
deposited. 
8 This organ, to which I first called the attention 
in the dissertation of Bagge (De evolutione Stron- 
gyli auricularis et Ascaridis acuminatae, 1841, p. 
13), is composed of two canals which run back- 
wards in Strongylus auricularis, Ascaris brevi- 
caudata, and acuminata (Bagge, loc. cit. fig. 30, 
A. B.); and in Ascaris dactyluris, and pauci- 
para, mihi (from the intestine of Testudo graeca), 
of two anterior and posterior canals, the common 
opening of which is near the middle of the body. 
