ENTOZOA. 



95 



from their yielding 'to the pressure of the contained worm, and be- 

 coming elongated at the two points where the separation of the mus- 

 cular fasciculi most readily takes place, and offers least resistance. 



The innermost layer of the cyst can sometimes be detached entii*e, 

 like a distinct cyst, from the outer portion, and its contour is generally 

 well marked when seen by transmitted light. By cutting off the 

 extremity of the cyst, which may be done with a cataract needle or 

 fine knife, and gently pressing on the opposite extremity, the Tri • 

 china and the granular secretion with which it is surrounded, will 

 escape ; and it frequently starts out as soon as the cyst is opened. 



When first extracted, the Trichina is usually disposed in two or 

 two and a half spiral coils ; when straightened out it measures ^Lth 

 of an inch in length and ^^,»th of an inch in diameter, and now 

 requires for its satisfactory examination a magnifying power of at 

 least 200 linear admeasurement. 



The worm (^fig. 42.) is cylindrical and 

 filiform, minutely annulated, terminating 

 obtusely at both extremities, which are of 

 unequal sizes ; tapering towards one end 

 for about one-fourth part of its length, 

 but continuing of uniform diameter from 

 that point to the opposite extremity which 

 is trilabiate. 



The free canal, which commences or is 

 attached by a capillary tube or filament, at 

 the small end {Jig. 42. a.), rapidly widens 

 and presents a saccular form through one 

 half of its course : it is then continued of 

 a more slender and equable form to the 

 great end. At the junction of the saccular 

 H with the slender part, ft, of the canal 

 there are, according to Luschka*, two 

 small coeca. Near these is the blind end, 

 of a second canal which contains the small 

 cluster of minute dark granules f, and is 

 continued to the trilabiate end of the body; 

 Luschka :f believes both tubes to terminate 

 here in a blind end. 



The worm has no organic connection 



Trichina spiralis, magnified. ^-^^^ ^^^ ^^^^ . sometimes t WO TrichincB, 



rarely three, occur in the same cyst. 



* LXXXm p. 77. taf. iii. fig. 5. c c. f LXXXIV. p. 63., and LXXXV. 



% This author seems only to have read LXXX., and to have been tinacqxiainted 

 with the additional observations on the " Anatomy of the Trichina," in LXXXIV. 



