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VIII. On the Structure and Develojpment of the Cysticercus cellulosee, as found in the 
Muscles of the Pig. By Geoege Eainey, M.R.C.S.., Lecturer on Anatomy and 
Demonstrator of Practical and Microscopical Anatomy at St. Thomas’s Hospital. 
Communicated by R. D. TnoMSOisr, M.D., F.R.S. 
Eeceived January 16*, — Read March 19, 1857. 
I AM aware that this parasite has been found in various other animals besides the Pig, 
also that it occasionally infests the human subject, but as I have not had the opportu- 
nity of examming it m the latter, and as my opportunities of investigating its structure 
and development in the former have been very abundant, I shall confine my observations 
to this entozoon as it occm’s in the Pig. 
The Cysticercus in its developed state is found chiefly in the ordinary muscles lodged 
in the cellular intervals between the fibres, also on the surface of the muscles imme- 
diately beneath theu fascial investment. These parasites infest the heart in as great abun- 
dance as other muscles composed of striped fibres, where they are situated, some in the 
substance of the walls of the auricles and ventricles, others directly beneath the pericardium 
between it and the muscular fibres, and others just under the endocardium. They occur 
also in the muscular coat of the oesophagus, almost as low down as the stomach. But as 
in the Pig the striped fibres extend nearly to the inferior extremity of this tube, the 
presence of Cysticerd there forms no exception to their usual position in muscles composed 
of striped fibres. I found but very few in the lower part of this tube, and as yet I have 
not met with them in the muscular coat of the intestines, in that of the large vessels close 
to the heart, in any of the glandular organs, nor in any of the structures of the lungs. 
However, in one pig, very much infested with them, I found one Cysticercus under 
the mucous membrane of the larynx, also one behind the peritoneum near to the kidney. 
As these appear to be probably only accidental cases, I am inclined to regard the striped 
muscles as the true seat of this species of Cysticercus. 
This Cysticercus.^ when sufiiciently developed to be apparent without the aid of the 
microscope, is seen to consist of an oval cyst, about half an inch in length, having a 
white globular body in its centre ; but if the muscle in which these animalcules are con- 
taiued has been exposed for a few hours to the ah’, the white bodies will be the only 
part very distinctly visible ; the cysts in this case having become collapsed from the 
evaporation of their fluid. If, however, the muscle be put into water for a short time, 
the cysts will become redistended, and rendered as apparent as before. As often as 
* The observations described in this paper were originally communicated to the Royal Society on the 
27th of June, 1855. See Proceedings of the Royal Society for December 13, 1855. 
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