578 DESCRIPTION OF THE 8UBGENUS ECHINOCOCCIFER. 



tape-worm is, however, of small size, even in such colossal specimens, 

 and is hardly longer than 10-15 mm. even when extended. 



The form as well as the size of the bladder is subject to many 

 variations. This is especially true of the ratio between the length 

 and the transverse diameter, which varies so much that the worms are 

 sometimes spherical and sometimes longitudinally extended. Moniez 

 mentions a specimen which was from 6 to 7 cm. in length, but hardly 

 1*5 cm. broad. Under these circumstances, one might almost guess 

 that the Cysticercus fistularis from the horse, described by Eudolphi 

 as possessing a length of 4 to 5 inches and a breadth of 3 to 4 lines, was 

 nothing else than a longitudinally extended Cysticercus tenuicollis. 

 In another specimen, Moniez observed at some distance behind the 

 head a rag-like thickening of the bladder-wall, which measured almost 

 3 mm., and in its histological relations might be compared with a 

 segment of a Toenia. I owe to the kindness of Dr. Schmidt in Frank- 

 fort a Cysticercus tenuicollis of moderate dimensions, whose interior 

 contained three sterile daughter-bladders of 2 to 3 mm. in diameter, and 

 which thus in some respects furnished a counterpart to the Cysticercus 

 racemosus already described (p. 554). 



In the dog the whole body of the bladder-worm is destroyed after 

 the feeding except the head and its neck. It is true that the solid 

 body of the worm is preserved for a time, and perhaps even longer 

 than in other bladder-worms, but this is not of the least significance 

 to the later Tsenioid body. From ten to twelve weeks generally elapse 

 before the expulsion of proglottides, while T. serrata only requires 

 eight weeks, and T. ccenurus becomes ripe even in three or four. 



B. Cystic Tape- Worms, vihose heads are "budded off from special brood- 

 capsules attached to the inner surface of the bladder. 



Subgenus Echinococcifer, Weinland. 



J. Mttller, Archiv f. Anat. u. Phyt., p. 107, 1836; MtttheU. VerkandL GescUsch. 

 naturf. Freunde, p. 17, 1836. 



Von Siebold, Burdach's " Physiologic," Bd. ii., p. 183, 1837. 



Huxley, " Anatomy and Development of Echinococcus veterinorum," Proc. Zod, 

 Soc., xx., p. 110, 1852. 



G. Wagner, " Entwickelung der Cestoden," Nova Acta Acad. Cces. Lcop.-CaroL, Bd. 

 xxiv., Suppl., p. 34, 1854. 



Eschricht, "Beretning om fortsatte UndersSgelaer af Echinokokkerne, " Overs, k. d. 

 Vid. Selsk. Fork., p. 127 ; Zeitsckr. f. d. ges. Naturwiss., p. 231, 1857. 



Krabbe, " Recherches helminthologiques en Danemark et en Islande," Copenhagen, 

 1866. 



In the cystic bladder-worms of the previous group the tape-worm 

 head originated from a hollow process, which might be regarded as 

 an invagination of the bladder-wall. In the worms of this second 



