25 



and from ^į-rth to ^v^th of an inch in diameter : a high magnifying 

 power is conseąuently required for its examination. It is round and 

 filiform, terminating obtusely at both extremities, which are of un- 

 equal sizes, and tapering tovvards one end for about a fifth part of its 

 length, biit continuing of uniform diameter from that point to the 

 opposite extremity. As it is only at the larger extremity that he has 

 been enabled to distinguish an indication of an orifice, Mr. Owen 

 regards that as the head. He statės that this indication has been so 

 constant in a number of individuals examined under every variety of 

 circumstance, that he has no hesitation in ascribing a large transverse 

 linear orifice or mouth to the greater extremity, 



The recently extracted worm, observed by means of a Wollaston's 

 doublet, before any evaporation of the surrounding moisture has af- 

 fected its integument, presents a smooth transparent external skin, 

 inclosing a fine granular and flaky substance or parenchyma. It is 

 obvious that the tęst of coloured food cannot here be applied to elu- 

 cidate the form of the digestive organs, but there is no appearance 

 of the parietės of an alimentary canal floating in a visceral cavity and 

 distinet from the integument of the body, nor was any trace of an 

 orifice observed at the smaller extremity. Mr. Owen was also un- 

 able to detect in any instance a projecting spiculum or hook at 

 either extremity, or any appearance of the worra having been torn 

 from an attached cyst. Its transparency is such as not to admit of 

 a doubt as to its wanting the ovarian and seminal tubes, and the 

 otlier characteristics of the complicated structure of Filaria, Ascaris, 

 and the Nematoid Entozoa generally. It is not of a rigid texture, but 

 is extremely fragile, and exhibits \vhen uncoiled a tendency to return 

 in some degree to its former statė. 



Mr. 0\ven refers to the genus Capsularia as established by Zeder, 

 and rejected by Rudolphi, (who considers its species as belonging 

 either to Filaria or Ascaris,) for the purpose of contrasting the 

 complicated organization of the worms composing it with the ex- 

 tremely simple structure of the encysted worm under considera- 

 tion. The circumstance of being inclosed in cysts he stated to be 

 common to many very differently organized genera of Entozoa. 

 There are few, indeed, with the exception of those which live upon 

 the mucous surfaces of the body, that do not, by exciting the adhe- 

 sive inflammation, become inclosed within an adventitious cyst of 

 condensed cellular substance. He regards the simple type of struc- 

 ture exhibited by the minute animal now for the first time described 

 as approximating it to the lower organized groups of the Vers Pa- 

 renchymateux of Cuvier ; and both from its locality and from the 

 constancy of its cysts, he regards it as manifesting a relation of 

 analogy to the order Cystica of Rudolphi. From all the genera of 

 that order, however, it difFers in the want of the complex armature 

 of the head, and of the dilated vesicle of the tail. At first sight it 

 seems indicative of an aimectant group which would complete the 

 circular arrangetnent of the Entozoa by combining the form of the 

 Filariee of the first, with some of the characteristics of the Cysticerci 

 of the lašt, of Rudolphi's orders. Unfortunately the class Entozoa, 



