104 THE HELMINTHES. § 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 Ec/mwcoccus, 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 ; 

 Strong^y/vs annulatus, milii (from the trachea and the whole is a thick membrane, resembling 

 of the wolf). coagulated albumen and composed of numerous 



The epidermis of Ascari.i ni^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 Acauthocephali. It is here 



3 Excepting the longitudinal folds of the epider- really a vital act ; for Echinorhynchus, which 

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

 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. 20-2-1), I have as yet found the epi- Creplin (Nov. 01>serv. de Entozois. 1S29, p. 44, 

 dermis longitudinally plicated over the whole and in Ersch and Grube''s Encyclopaedic XXX. 

 body only -with StrongylusstriatuSjUiiAin/iexus. 1838, p. 384), hy Mehlis (Isis. 1831, p. 167), and 



■* These different dermic layers are distinct, espe- by myself. With the Nematodes it is otherwise, 



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



din'x figure in the Ann. d. Sc. Nat. XVIII. 1842, power, and when, therefore, they are put in water, 



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



ris myHax,microcephala, Distomum echina- cei this power is purely physical, so that the dead 



tvm, hians, linea, and in Monostomum verru- and dried individuals of Gordius aquaticus, when 



cosum. placed in water, quickly become round again, and 



In Amphistomum g'iganteum, Diesing (Annul, perform very active hydroscopic motions. 



d. Wiener Museums, I. Abth. 2, p. 239, Taf. XXII. 1 These calcareous corpuscles, which are always 



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



lar. The same is true of Bojanus (Isis, 1S21, p. 166, whole body of these Helminthes, have been taken 



Taf. II. fig. 12), and Luurer (De Amphistomo by Pallas, Goeze, Zeder, and by most Helmin- 



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



But the structure of the skin of Echinococcus often figured. 



