104 THE UELMINTIIES. § 101. 



to other animals, and therefore will be specially described with the locomo- 

 tive organs. 



With most of the Nematodes, the epidci'mis has very line 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 

 form3. 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 This is so, for instance, with the anterior is quite different. Here no epidermis can be 

 extremity of Liorhynchus denticulatus, and separated from the dermis or the sac of the body ; 

 Strongylus annulatus, niihi (from the trachea and tlie whole is a tliiclc membrane, resembling 

 ofthewulf). coagulated albumen and composed of numerous 



The epidermis of Ascaris nit^-rovenosa has such very thin layers, tightly bound together, 



long and loose folds that its body, seen laterally, 5 This absorbent power of the skin is particularly 



has a fringed appearance. prominent with the Acanthocephali. It is here 



3 Excepting the longitudinal folds of the epider- really a vital act ; for Echinor/ii/nc/iu.i, which 

 mis, which form lateral wings of variable form and naturally absorbs oidy a little liquid into its cou- 

 length at the cephalic extremity of the Nematodes, stantly flattened and wrinkled body, swells and 

 or on both sides of the extremity of the tail of many relaxes alternately when in contact with water, 

 males of this order (Bremser, Icon. Helminth. This has been observed with many species by 

 Tab. IV. fig. 20--24), I have as yet found the epi- Creplin (Nov. Observ. de Entozois. 182J, p. 44, 

 dermis longitudinally plicated over the wliole and in Ersch and Grube''s Encyclopaedic XX.X. 

 body on\y with atrong-i/lusstriatuSfSiXKliii/lexus. 1838, p. 384), by JI/eA/iS (Isis. 1831, ]>. 16V), and 



■* These ditf.-rent dermic layers are distinct, espe- by myself. ^Vith the Nematodes it is otherwise, 



cially with Gordius and Mermis ; see Diijar- These cannot voluntarily govern this absorbing 



d(?('.s figure in the Aim. d. Sc. Nat. XVIII. 184'2, power, and when, therefore, they are ])ut in water, 



PI. VI. I have found this structure also in Asca- they swell to bursting and die. 'With the Gordia- 



Tis myslax,microcephala, Disto7num echina- cei this power is purely physical, so that the dead 



tuw, hians, linea, and in Monostomum verru- and dried individuals of Uordius aqualicus, when 



cosum. placed in water, (juickly become round again, and 



In Amphistommn gisanlemn,Diesing (^kxmaX. perform very active hydroscopic motions. 

 d. Wiener Museums, I. Al)th. 2, ]>. 239, Taf. X.XII. i These calcareous corjiuscles, which are always 



fig. 1, c, d), has regarded these layers as muscu- without an enveloi)e and are scattered through the 



lar. The same is true of /Jo/an M,s (If'?, 1821, p. 166, whole body of tliese Helminlhes, have been taken 



Taf. II. fig. 12), and Laurer (De Amphistomo by Pallax, Gneze, Zeder, and by most llelmin- 



conico, p. 6, fig. 15). thologists until lately, for eggs, and aa such were 



liut. the structure uf the skin of Echinococcus often figured. 



