TKICHINA SPIKALIS. 339 



vascular net, which may be particularly well traced by direct 

 light, and which probably effects the conveyance of nutriment less 

 by direct transudation, than by similar processes to those with 

 which we have become acquainted amongst the encysted brood 

 of the Tcenite. 



The inner, nearly homogeneous, or but sparingly fibrous or 

 granular layer, which is always roundish, resists the action of 

 caustic potash, acetic acid, and muriatic acid ; it is very rich in 

 calcareous corpuscles, and belongs rather to the Trichina itself, 

 but is probably rather agglutinated, than truly coalescent with 

 the outer envelope, as may be seen from perpendicular sections 

 which show a distinct separation of the lwo layers, and from their 

 partial separation in consequence of treatment with muriatic acid. 

 That this enveloping layer is derived from the animal itself, I am, 

 for my own part, as firmly convinced as Luschka, and I only 

 regret that I could not detect the same in those capsules of 

 Trichina which enclose two or more worms in common, that 

 Meissner has done for analogous cysts of Gordii with twins. 

 Thus, according to the latter, each young Gordius is enclosed in 

 a cyst formed by the worm itself, within the cyst formed by the 

 host. In Meissner's fig. 36, PI. VII, we distinctly recognise 

 the outlines of these separate envelopes formed by the worm, 

 especially at the spots between the two worms where these cysts 

 cover each other. Perhaps it is owing to my clumsiness that I 

 could not find these separate cysts, and others will perhaps suc- 

 ceed in furnishing this proof; or they may not exist at all or at 

 any time in this Trichina, or, lastly, they may be absorbed again 

 in the places between the worms, in most, and especially in the 

 older cases, which is by no means improbable. 



Gairdner found Trichina in all the transversely striated 

 muscles ( f Monthly Journ. of Med. Science/ May, 1853, p. 473). 

 Sanders and Kirk state that there are around the worm — 1, 

 an external fibrous envelope ; 2, a tolerably thick layer of a 

 white, transparent, homogeneous substance ; and 3, an internal 

 round capsule. These observers frequently saw a small cyst 

 lying upon a large one, and in two cases a small round vesicle 

 at the narrow end of the cyst. 



The contents of the cysts consist of one or more animals, and 

 a small quantity of fluid, which keeps the inner envelope extended. 

 The fluid is sometimes clear, as in Kobelt's and Zenker's cases, 

 because the Trichinae in these were comparatively young; some- 



