104 



THE HELMINTHE3. 



^101. 



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 calcareous net-works found in the skin of many Polyps and 

 Echinoderms. 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.''' 



2 Tliis is so, for instance, with the anterior 

 •extremity of Liorliynchiis denticulatus, and 

 ■Strong-ylus annulatus, mihi (from the trachea _ 

 of the wolf). 



The epidermis of Ascarix ni^rovenosa 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 Nematodes, 

 or on both sides of the extremity of the tail of many 

 males of this order (Bremser, Icon. Helminth. 

 Tab. IV. fig. 20-2i), I have as yet found the epi- 

 -dermis longitudinally plicated over the whole 

 ■body only with Strongijlus striatus, and inflexus. 



4 These difl'orent dermic layers are distinct, espe- 

 <;ially with Qordius and Mermis ; see Diijar- 

 ■dhi's figure in the Ann. d. Sc. Nat. XVIII. 1842, 

 PI. VI. I have found this structure also in A.ica- 

 ris my.slax, microcephaLa, liistomuTn echina- 

 tum, hians, linea, and in Monostomum verru- 

 coKum. 



In Amphistomum /^i^anleitm, Diesing (Annal. 

 <J. 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 Bnjanus (Isis, 1821, p. 166, 

 Taf. II. fig. 12), and Laurer (Ue Amphistouio 

 conico, p. 6, fig. 15). 



But the structure of tlie skin of Echinococcus 



is quite diflferent. Here no epidermis can be 

 separated from the dermis or the sac of the body ; 

 and the whole is a thick membrane, resembling 

 coagulated allmmen and composed of numerous 

 very tliiu layers, tightly bound together. 



•5 Tliis aljsiirbent power of the skill is particularly 

 prominent with the Acanthocephali. It is here 

 really a vital act ; for Echiriorhy nchiis , which 

 naturally absorbs only a little Uquid into its con- 

 stantly flattened and wrinkled body, swells and 

 relaxes alternately when in contact with water. 

 This has been observed with many species l)y 

 Crepliii (Nov. Observ. de Entozois. 1823, p. 4-t, 

 and in Ersch and Grube^s Encyclopajdie XXX. 

 1838, p. 384), by MekUs (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 jjut in water, 

 they swell to bursting and die. With the liordia- 

 cei this power is purely ]iliysjcal, so that tlie dead 

 and dried individuals of Uordiiis (Kiu/Uiciift, when 

 placed in water, tiuickly become round again, and 

 perform very active hydroscopic motions. 



' These calcareous corpuscles, which are always 

 without an envelojie and are scattered through the 

 whole body of these Helniinthes, have been taken 

 by PaUas, Got ze, Zeder, and by most Ilelmin- 

 thologists until .Htely, for eggs, and as such were 

 often figured. 



