
INFESTING THE MUSCLES OF THE HUMAN BODY, 321 
immediately engaged in physiological investigations. It recently happened that two 
medical gentlemen having sat down to partake of a cod’s head and shoulders, were dis- 
agreeably interrupted in their repast by the appearance of a large lively round worm, 
which on the first cut into the fish escaped therefrom, and began to coil and uncoil itself 
on the edge of the dish. Now this worm must have been submitted to the temperature 
of boiling water for at least half an hour, and the Entozoa would thus appear to en- 
dure with impunity extremes alike of cold and heat. 
With respect to the cyst of Trichina spiralis, I was at first inclined, from the prevailing 
regularity of its figure, to believe it to be the Entozoon itself, or a part of the Entozoon 
analogous to the dilated tail of the Cysticerci. Mr, Hilton, Demonstrator of Anatomy 
at Guy’s Hospital, who appears to have first recorded this affection of the human 
muscles', ascribed it to the presence of a minute species of Cysticercus, not being 
aware of the existence of the animal to which the presence of the cysts in question is 
owing. The difference, however, between the parasitic animals under consideration and 
the Cysticerci, is at once obvious ; the true Cysticerci are always inclosed within an 
adventitious cyst of cellular membrane, in which the Hydatid either freely floats, or at 
most adheres to the inner surface by the mouth only ; whereas the present cysts, besides 
the absence of the peculiar structure and pearly subtransparency which characterize 
the true Hydatid, adhere to the surrounding parts by the whole of their exterior, which 
is covered by a cellular flocculency. 
But admitting the similarity of the outer cyst of Trichina to the outer adventitious 
cyst of Cysticercus, it may be contended that the inner cyst is part of the organization 
of the inclosed worm. Its analogy to the second cyst of the genus Anthocephalus, 
within which the elongated body of that worm is seen, readily occurs, but will not hold 
good on a close examination. The elongated body of Anthocephalus is always found in 
organical connexion with the second cyst; and Rudolphi observes, that the point of 
continuity is indicated externally by a depression occasioned by the inversion of the 
body at that part. In the Oysticerci a similar appearance is frequently observed, from 
the inversion of the head and body within the terminal cyst ; and in the Cenuri, where 
the corresponding bladder is common to many armed heads, some of these are 
generally found inverted, while others are projecting externally. In all these cases, 
however, besides the difference of structure between the second and outer cyst, they 
are always perfectly distinct from each other, and readily separable. But I have never 
been able to effect a corresponding separation between the outer and supposed inner 
cyst of Trichina, or to demonstrate satisfactorily the existence of the latter as a distinct 
' See ‘Medical Gazette’ for February 2, 1833, p. 605. In a letter from Mr. Hilton to Thomas Bell, Esq., 
which the latter distinguished naturalist has kindly communicated to me, it is stated that three subjects, with 
the muscles similarly affected, have been brought to the dissecting-room at Guy’s Hospital during the present 
season (1834—5). 
