EBONY. 



[ 218 ] 



ECHINOCOCCUS. 



tip of the maxillae, and seven-jointed. The 

 labial palpi (/) are slender and four-jointed, 

 the first and third joints being very short. 



The head of the larva, and the three pairs 

 of legs of the perfect insect, are commonly 

 mounted as microscopic objects, as are those 

 of other genera belonging to this family, — 

 Acilius, &c. 



BiBL. Westwood, Introduction, &c. i. p. 

 95 ; Stephens, British Beetles. 



E. 



EBONY. — The heart-wood of species of 

 Diospyros (Ebenacese, Dicotyledons), re- 

 markable for its solidity and black colour. 

 See Wood. 



ECCRINA, Leidy. — See Enterobryus. 



ECHINELLA, Acharius. — A term applied 

 first to a group of ova of some aquatic 

 animal, next to a genus of Infusoria, more 

 recently to a genus of Diatomacese, but now 

 no longer used. 



ECHINOBOTRYUM, Corda.— A genus 

 of Torulacei (Coniomycetous Fungi). E. 

 atrum has been found in Britain parasitic 

 upon a species of Pachnocyhe. 



BiBL. Berk, and Broome, ^ww. ISIat. Hist. 

 2 ser. v. p. 466; Corda, Icon. Fung. ii. fig. 6. 



ECHINOCOCCUS, Rud.— A supposed 

 genus of Entozoa, of the order Sterelmintha 

 and family Cystica ; recently shown to con- 

 sist of the larvae of Tcenia. 



Char. Consisting of a vesicle of very 

 variable size, sometimes sm'rounded bv a coat 

 of condensed areolar tissue, and containing 

 within, one or more secondary cysts ; 

 attached to the inner wall of these cysts, or 

 suspended in their liquid contents, are 

 numerous oblong, rounded, or oval bodies, 

 each with four suckers, and a double crown 

 of hooks. 



E. veterinorum, the only species (PL 16. 

 figs. 1 & 2). Occm's in the liver, the cavity 

 of the abdomen, the heart, the voluntary 

 muscles, and the ventricles of the brain of 

 man; in the liver, lungs, &c. of the ox, sheep, 

 goat, ape, pig, &c. Commonly called hyda- 

 tids. The walls of the true cysts consist of 

 numerous concentric layers or plates, resem- 

 bling those of colloid cells or cysts. The 

 liquid existing within the cysts is yellowish 

 or reddish, albuminous, and frequently con- 

 tains plates of cholesterine, and crystals of 

 bilifulvine (PI. 9. fig. 15) (see Bile) ; some 

 of the latter resemble in form and colour 

 those of H^MAToiDiNE. The larva? appear 

 to the naked eye as minute white, opake 

 specks ; varying in size from about the 



1-300 to 1-100" in length. They also vary 

 greatly in form ; when the head is retracted 

 (fig. 1 a) they appear more roundedthan when 

 this is protruded (fig. 1 c. Id, If). The hooks 

 surrounding the anterior end of the body 

 (fig. 1 b) consist of a broadish basal portion, 

 an internal transverse blunt tooth, and a 

 curved terminal portion or claw ; thev are 

 about the 1-1500 to 1-1000" in length.' In 

 some of the larvas a kind of pedicle exists at 

 the base, by which they are attached to the 

 wall of the cyst (figs. 1 a and 1 c); sometimes 

 two or more lines may be perceived, running 

 from the head towards the pedicle, and con- 

 nected in front by a transverse line ; pro- 

 bably representing vessels (fig. 1 c). Inter- 

 spersed through the substance of the body, 

 are minute, highly refractive corpuscles con- 

 taining carbonate of lime. 



In the quite recent state, the lan^ae have 

 been seen swimming actively in the liquid of 

 the cyst; this motion is produced by cilia 

 existing upon the sm'face of the body. 

 Mingled with the perfect larvae are generally 

 found some in which neither hooks nor 

 suckers are visible, and in which the form is 

 very irregular ; some of these assume the 

 natural form, when treated with acetic acid. 



The larvae appear usually to be develo])ed 

 by gemmation from the interior of the cysts; 

 but as Kuhn long since showed, they are | 

 sometimes produced by external gemmation i 

 (fig. 2) : the contents produce a slight pro- " 

 trusion of a part of the wall of a cyst ; the 

 protruded portion enlarges, afterwards be- 

 coming constricted at its base, at last pro- 

 bably separating from the parent, to become 

 itself a parent in the same manner. The 

 contents of the new cysts in the above 

 instance were at first simply granular, in the 

 larger and more developed cysts, the hooks 

 were also present. Hence it appears that 

 the larvae cannot be regarded as the parasites 

 of a cyst, but must be viewed as arising from 

 a partial segmentation of the contents of the 

 parent. The example figm'ed in PI. 16. fig. 2 

 was not isolated; there were many, contained 

 with numerous other larger cysts, of the most 

 varied size, all in one very large parent-cyst. 



The Echinococci do not attain their full 

 development into TcenicB, unless thej^ reach 

 the alimentary canal. The cysts and their 

 contents, including the Echinococci, undergo 

 a kind of degeneration, becoming partially 

 converted into fatty or calcareous matter; 

 or the entire contents become amorphous 

 and granular, the hooks remaining longest 

 unaltered, but finally disappearing also. 



