176 CLASS VY. 
Tenia serrata, which in its developed state resides in the small 
intestine of the dog, was found in all cases. The experiments were 
performed so frequently, and with such precautions as to render the 
results incontestable’. The cyst is a secretion of the infested animal, 
and derives its blood-vessels from it. 
There is reason to conclude that a nervous system exists in 
most Entozoa. In Bothriocephalus BLANCHARD describes a small 
ganglion on each side of the head (probably connected by a trans- 
verse band), which sends a fine thread forwards and backwards ; but 
he was not able to detect the distribution of these®.] No nerves 
have been discovered in the incomplete cystic forms. In Distomes, 
and various other suctorial worms, two small ganglia have been 
seen near the mouth, which are united by a transverse band that 
runs over the cesophagus. From these two threads arise that have 
a parallel course through the body, become finer backwards, and 
give off some lateral branches*. In the thorn-headed worms there 
is, according to the investigations of VON SIEBOLD, in different 
species of Hehinorhynchus, a nervous mass at the base of the pro- 
boscis, from whence threads radiate in all directions, whose course 
is not easy to follow. In Pentastoma a large nervous ganglion lies 
beneath the cesophagus, from which a nervous ring arises that runs 
transversely above the cesophagus; small branches go from the 
ganglion to the muscles of the mouth and the surrounding parts, 
and two threads proceed longitudinally, one on each side, back- 
wards, giving off fine branches, and, at last, losing themselves in 
the muscular tissue*. In Strongylus gigas the nervous system forms 
a flattened ring round the commencement of the cesophagus, and a 
string running backwards in the middle of the abdominal surface, 
which ends in a ganglion close by the anus. From the string arise 
at short and nearly equal distances transverse nervous threads. 
Special organs of sense are not found in the intestinal worms, with 
1 See Band u. Blasen-w. s. 80—95. 
2 BLANCHARD Ann. des Sc. nat. 3e Série, Zool. Vol. XI. pp. 113, 114, CUVIER 
édit, illus. Zooph. pl. 26. fig. 1d. 
3 Meutts Observat. anat. de Distomate; Dinsine in Amphistoma gigantewm, Wiener 
Annalen 1. p. 146, Tab. xx. fig. 16, &e. 
4 Owren Transact. of the Zool. Soc. 1. pl. 41. fig. 13; Topp Cyclop. 1.1. p. 130, 
fig. 78 in Pentastoma tenioides; Dinstne Wiener Annal. 1. Tab. U1. figs. 7, 19, in 
Pentast. proboscidewn. 
