550 OCCURRENCE AND RESULTS OF CYSTICERCUS CELLULOSE. 



psoas. The musculature of the ventricles and auricles was frequented, 

 as was also the inner layer of the pericardium and endocardium. 

 Under the superficial membrane, the bladder-worms not unfrequently 

 form vesicular dilatations, and (especially in the endocardium) papillar 

 or stalked appendages ; and a Cysticercus has been observed even in 

 the walls of the blood-vessels. 



Of special interest is the occurrence of Cysticerci in the eye, partly 

 because it is common and soon makes itself perceptible, partly also 

 because it affords opportunity for observing the worm in its natural 

 environment, and of following out its development. We owe this to 

 the discovery and application of the ophthalmoscope, and the sensation 

 which its revelations excited was all the greater since previous experi- 

 ence of bladder-worms in the eye had been limited to but few cases. l 



Von Graefe, to whom we owe our first account of these surprising 

 discoveries, calculates, on the strength of a very large mass of statistics, 2 

 that the occurrence of the Cysticercus in the deeper parts of the eye at 

 about one per thousand among the patients at the Berlin Ophthalmic 

 Institute. In the anterior parts of the eye he only reports nine 

 cases (five in the conjunctiva, two in the anterior chamber, one in the 

 lens, and only one in the orbit) ; but these represent hardly the eighth 

 part of those found in the vitreous humour, or in the subretinal 

 tissue. Those in the latter situation are by far the most frequent, 

 standing to those found in the vitreous humour in the ratio of 2 : 1. 



In the cases mentioned by v. Graefe it was always only a single 

 Cysticercus which inhabited the eye ; and so also with others, with 

 the exception of a single case observed by 0. Becker, where one 

 Cysticercus occurred in the vitreous humour and another in the 

 retina. This solitary mode of occurrence is peculiar to man, for in 

 the pig the eye occasionally contains a considerable number. Xord- 

 inann counted in one case twelve, of which six were in the vitreous 

 humour, and the other six between the sclerotic and the choroid. 3 



In the chambers of the eye the Cysticercus is almost always 

 free i.e., without a capsule, and swimming in the fluid ; so that its 

 position may vary with the attitude of the head and the direction of 

 the eyes, as well as with its own movements, which consist partly of 

 an undulating peristalsis of the bladder, but principally of an alternate 

 protrusion and retraction of the head. At the point of insertion of 



1 The first observation on the occurrence of a bladder-worm in the eye (the anterior 

 chamber) is furnished by Schott and Sommering. Oken's Isis, p. 717, 1830. 



2 From the Verkandl. Berlin. Med. Geaellsch., 1867-68, p. 96, 1871, I extract the 

 statement that v. Graefe has observed over 100 cases of bladder-worms in the eye. The 

 observations in the text rest on v. Graefe's notes on Cysticercus (Archiv f. ophthalmdoyie, 

 Bd. xii, p. 174). 



8 Mikrographische Beitrage, Th. i., p. 13 : Berlin, 1832. 



