TRICHINA SPIRALIS. 335 



25. Trichina spiralis. 



T. spiralis, Owen ; Farre ; Henle ; etc. 

 Pseudalius Trichina, Davaine. 



General and Specific Characters. — An extremely minute nematode helminth, the male in 

 its fully developed and sexually-mature condition measuring only the -rV of an inch, whilst 

 the perfectly developed female reaches a length of about ^" ; body rounded and filiform ; 

 usually slightly bent upon itself, rather thicker behind than in front, especially in the 

 males ; head narrow, finely pointed, unarmed, with a simple, central, nainuto oral 

 aperture ; posterior extremity of the male furnished with a bilobed caudal appendage, 

 the oloacal or anal aperture being situated between these divergent appendages ; penis 

 consisting of a single spicule, cleft above, so as to assume a V-shaped outhne ; female 

 stouter than the male, bluntly rounded posteriorly, with the genital outlet placed far for- 

 ward, at about the end of the first fifth of the long diameter of the body ; eggs measur- 

 ing j-jVo" from pole to pole ; mode of reproduction viviparous. 



So familiar is the Bnglisli reader with, the circumstances attending 

 the early history and discovery of this parasite, that it is unnecessary 

 to do more than glance at this part of our subject. The Trichinae ori- 

 ginally discovered by Owen in a portion of human muscle transmitted 

 to him by Mr. Wormald of St. Bartholomew's Hospital, we now 

 know to represent merely the larval condition of the adult nematode 

 worm whose characters are briefly given above. It detracts nothing 

 from the merit of Owen, that these httle worms have turned out to be 

 only the wandering brood of a more highly organized nematode ; 

 but, independently, the discovery gathers additional importance from 

 the fact that, prior to the publication of Owen's observations, the 

 calcareous cysts enveloping the Trichinae had been noticed by seve- 

 ral observers on the Continent, who, not having examined them 

 with sufficient care, appear to have jumped to the conclusion that 

 they ought to be regarded merely as evidences of muscular 

 degeneration. To my mind, this discovery is one of the happiest 

 to which the English helminthologists can point, for, apart from 

 its intrinsic interest, it has led to the most important practical 

 results. 



It is not, indeed, a little curious and instructive to note, in 



