EARLY STAGES OF CYSTICEKCUS CELLULOSE. 499 



1. The Bladder-worm {Cysticercus cdlulosce). 



As to the fate of the embryos, and the ways by which they pass 

 from the intestine to the muscles or organs they inhabit, we have un- 

 fortunately but few definite results, but are left to inductive conclu- 

 sions, which are rendered somewhat doubtful by the limited range and 

 uncertainty of our experiments (p. 339). 



The youngest worms we know were seen eight days after the 

 feeding. I have myself sought in vain for these first larval stages. 

 Over and over again I extracted portions of muscle from the subjects 

 of my experiments eight or ten days after the introduction of the eggs, 

 and once sacrificed a whole pig for this purpose fourteen days after 

 the first feeding and twelve after the second, but without result. This 

 blank has, however, been filled up by Hosier's researches. ^ He de- 

 scribes the young bladder-worms as oval vesicles 0'033 mm. long, and 

 0'024 mm. broad, only slightly larger, therefore, than the former 

 embryos, but further differentiated in that they enclosed granular 

 contents. The six hooks seemed already lost, if one may so infer 

 from his silence regarding them. There was no proper capsule ; the 

 worms lay quite free between the muscular fibres. It was only in the 

 heart that Hosier found these parasites after he had looked through 

 all the muscles of the body in vain. The heart was examined with 

 special care, since the animal had eaten some trichinous fiesh in 

 addition to the 180 proglottides, and the Trichince were looked for 

 specially in the heart. 



What Hosier has said here is by no means the only existing 

 observation on the first young stages of the bladder-worm of the 

 pig. A decade before, an English investigator, Eainey, also found 

 them.^ He describes them, however, not as free vesicles, but as 

 spindle-shaped tubes, lying inside the muscle-bundle, bearing a thick 

 coating of bristles, and enclosing countless small kidney-shaped bodies. 

 According to him the latter are the beginnings of the 'tubes ; they 

 are said to collect inside the muscular bundle, and then subsequently 

 to become surrounded with an envelope. After the tube has remained 

 for a while in its place of formation, it is liberated by the bursting of 

 the muscular bundle. Shortly afterwards it casts its skin ; the coating 

 of bristles is thrown off, and the contents become, by coalescence of 

 the corpuscles, a tolerably homogeneous granular mass. At the same 

 time the parasite loses its former slender form. It becomes a roundish 

 vesicle, which develops about it a connective-tissue cyst, under shelter 



' Loc. at., p. 52. 



' "On the Structure and Development of the Cysticercus cellulosaa," PAiY. Trans., 



vol. oxvii., p. 114, 1857. Digitized by Microsoft® 



