114 



ENTOZOA. 



Fig. 53. 



This singular Entozoon I discovered in a 

 portion of the muscles of a male subject, which 

 was transmitted to me for examination, at the 

 beginning of 1835, by Mr.Wormald, Demon- 

 strator of Anatomy at St. Bartholomew's Hos- 

 pital, on account of a peculiar speckled ap- 

 pearance of those parts. This state of the 

 muscles had been noticed by that gentleman 

 as an occasional but rare occurrence in subjects 

 dissected at St. Bartholomew's in several pre- 

 vious years. 



The portion of muscle was beset with minute 

 whitish specks, as represented in the subjoined 

 cut (Jig. 53) : and in fourteen subsequent 

 instances which have 

 come to my knowledge 

 of the presence of this 

 entozoon in the human 

 subject, the muscles 

 have presented very 

 similar appearances, 

 The specks are produ- 

 ced by the cysts con- 

 taining the worm, and 

 vary, as to their dis- 

 tinctness, according to 

 their degrees of opacity, 

 whiteness, and hard- 

 ness. 



The cysts are very 

 readily detected by 

 gently compressing a 

 thin slice of the infect- 

 ed muscle between two 

 pieces of glass and ap- 

 plying a magnifying power of an inch focus. 

 They are of an elliptical figure, with the extremi- 

 ties more or less attenuated, often unequally 

 elongated, and always more opaque than the body 

 or intermediate part of the cyst, which is, in 

 general, sufficiently transparent to shew that 

 it contains a minute coiled-up worm. 



The cysts are always arranged with their 

 long axis parallel to the course of the mus- 

 cular fibres, which probably results from their 

 yielding to the pressure of the contained worm, 

 and becoming elongated at the two points 

 where the separation of the muscular fasciculi 

 most readily takes place, and offers least re- 

 sistance ; and for the same reason one or both 

 of the extremities of the cyst 

 Fig. 54. become from repeated pressure 

 and irritation thicker and more 

 opaque than the rest. That the 

 adhesive process in the cellular 

 tissue, to which I refer the for- 

 mation of the cyst, was most 

 active at the extremities of the 

 cyst is also evinced by the closer 

 adhesion which these parts have 

 to the surrounding cellular tissue. 

 The cysts measure generally 

 A separateCyst about 5 \jth of an inch in their 

 longitudinal, and -j^thof an inch 

 in their transverse diameters : 



like other c y sts which are the 



tranparent resu ^ OI tn e adhesive inflamma- 

 coats, magni- i}On > tn ey have a rough exterior, 

 jied. and are of a laminated texture. 



Cysts of the Trichina 



Spiralis in situ, natural 



site. 



of the Trie hi- 

 na. which is 



The innermost layer (Jig. 54), however, can 

 sometimes be detached entire, like a distinct 

 cyst, from the outer portion, and its contour 

 is generally well marked when seen by trans- 

 mitted 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 Trichina and the granular secre- 

 tion with which it is surrounded, will escape ; 

 and it frequently starts out as soon as the cyst 

 is opened. But this delicate operation requires 

 some practice and familiarity with microsco- 

 pical dissection, and many attempts may fail 

 before the dissector succeeds in liberating the 

 worm entire and uninjured. 



When first extracted, the Trichina is usually 

 disposed in two or two and a half spiral coils : 

 when straightened out (which is to be done 

 with a pair of hooked needles, when the sur- 

 rounding moisture is so far evaporated as that 

 the adhesion of the middle of the worm to the 

 glass it rests upon shall afford a due resistance 

 to a pressure of the needle upon the extremi- 

 ties), it measures ^th of an inch in length and 

 T^th f an inch i n diameter, and now requires 

 for its satisfactory examination a magnifying 

 power of at least 200 linear admeasurement. 

 The worm (fig. 55) is cylindrical and fili- 

 form, terminating obtusely 

 Fig. 55. at both extremities, which 



are of unequal sizes ; taper 

 ing towards one end for 

 about one-fourth part of its 

 length, but continuing of 

 uniform diameter from that 

 point to the opposite ex- 

 tremity. 



Until lately it was only 

 at the larger extremity that 

 Trichina spiralis I have been able to distin- 

 magnijied. guish an indication of an 



orifice, and this is situated 

 in many specimens in the centre of a transverse, 

 bilabiate, linear mouth, (, Jig. 54.) 



A recently extracted living worm, when ex- 

 amined by a good achromatic instrument be- 

 fore any evaporation of the surrounding fluid 

 has affected the integument, presents a smooth 

 transparent exterior skin, inclosing apparently 

 a fine granular parenchyma. It is curious to 

 watch the variety of deceptive appearances of 

 a more complex organization which result from 

 the wrinkling of the delicate integument. I 

 have sometimes perceived what seemed to be 

 a sacculated or spiral intestine ; and, as eva- 

 poration proceeds, this has apparently been 

 surrounded by minute tortuous tubes ; but the 

 fallacy of the latter appearance is easily de- 

 tected. A structure, which I have found in 

 more recent and better preserved specimens 

 than those which were the subjects of my first 

 description, is evidently real, and may pro- 

 bably belong to the generative system of the 

 Trichina ; it consists of a small rounded cluster 

 of granules of a darker or more opaque nature 

 than the rest of the body ; it is situated about 

 one-fifth of the length of the animal from the 

 larger or anterior extremity, and extends about 

 half-way across the body. 



