104 § 101. 
THE HELMINTHES. 
to other animals, and therefore will be specially described with the locomo- 
tive organs. 
With most of the Nematodes, the epidermis has very fine and closely 
approximated transverse folds, which are but occasionally so prominent 
that the body appears annulated.” Sometimes, but rarely, the body is also 
plicated in a longitudinal manner.® The dermis has a fibrous structure, 
consisting of two fibrous layers, — one longitudinal and the other transverse, 
—which cross each other at right angles; and of two other layers, which 
intersect each other more acutely.“ The skin of these animals has a 
great absorptive power which during life is voluntary, but which contin- 
ues to a certain extent after death, so that then these worms often swell 
enormously, and sometimes: burst. 
§ 101. 
Directly beneath the skin of the Cystici, and Cestodes, are found hard 
corpuscles containing carbonate of lime, and which may be regarded as the 
vestige of a cutaneous skeleton. But, as they are scattered here and there 
more deeply in the parenchyma, they certainly may be compared to the 
spicula and calcaréous net-works found in the skin of many Polyps and 
Kchinoderms. Oval or discoid, they are usually of equal size in the same 
individual. Sometimes, however, they present irregular and unequal 
forms. Always colorless and transparent, and composed of concentric 
layers, they refract the light like small vitreous bodies. 
In Taenia, Triaenophorus, Bothriocephalus, and the young of Echino- 
coccus, they are subcutaneous, and more or less scattered; but in the 
wrinkled and vesicular body of Coenurus, and Cysticercus, they are so very 
abundant that they form quite thick layers. They are absent in the cau- 
dal vesicle of Cysticercus, but in Coenurus, and Echinococcus, they are 
found in the vesicular walls beneath the delicate epithelium which lines the. 
interior of the body.” 
2This is so, for instance, with the anterior 
extremity of CZiorhynchus denticulatus, and 
Strongylus annulatus, mihi (from the trachea 
of the wolf). 
The epidermis of Ascaris nigrovenosa has such 
long and loose folds that its body, seen laterally, 
has a fringed appearance. 
3 Excepting the longitudinal folds of the epider- 
mis, which form lateral wings of variable form and 
length at the cephalic extremity of the N d 
is quite different. Here no epidermis can be 
separated from the dermis or the sac of the body ; 
and the whole is a thick membrane, resembling 
coagulated albumen and composed of numerous 
very thin layers, tightly bound together. 
5 This absorbent power of the skin is particularly 
promi with the Acanthocephali. It is here 
really a vital act ; for Echinorhynchus, which 
naturally absorbs only a little liquid into its con- 
or on both sides of the extremity of the tail of many 
males of this order (Bremser, Icon. Helminth. 
Tab. IV. fig. 20-24), I have as yet found the epi- 
dermis longitudinally plicated over the whole 
body only with Strongylus striatus, and inflexus. 
4 These different dermic layers are distinct, espe- 
cially with Gordius and Mermis; see Dujar- 
din’s figure in the Ann. d. Sc. Nat. XVIII. 1842, 
Pl. VI. [have found this structure also in Asca- 
ris mystax, microcephala, Distomum echina- 
tum, hians, linea, and in Monostomum verru- 
cosum. 
In Amphistomum giganteum, Diesing (Annal. 
4d, Wiener Museums, I. Abth. 2, p. 239, Taf. XXII. 
fig. 1, c, d), has regarded these layers as muscu 
lar. The same is true of Bojanus (Isis, 1821, p. 166, 
Taf. Il. fig. 12), and Laurer (De Amphistomo 
conico, p. 6, fig. 15). 
But the structure of the skin of Echinococcus 
stantly fi d and wrinkled body, swells and 
relaxes alternately when in contact with water. 
This has been observed with many species by 
Creplin (Nov. Observ. de Entozois. 1829, p. 44, 
and in Ersch and Grube’s Encyclopedie XXX. 
1838, p. 384), by Mehlis (Isis. 1831, p. 167), and 
by myself. With the Nematodes it is otherwise. 
These cannot voluntarily govern this absorbing 
power, and when, therefore, they are put in water, 
they swell to bursting and die. With the Gordia- 
cei this power is purely physical, so that the dead 
and dried individuals of Gordius aquaticus, when 
placed in water, quickly become round again, and 
perform very active hydroscopic motions. 
1 These calcareous corpuscles, which are always 
without an envelope and are scattered through the 
whole body of thes#Helminthes, have been taken 
by Pallas, Goeze, Zeder, and by most Helmin- 
thologists until ‘ately, for eggs, and as such were 
often figured. . 
