288 ANIMAL PAEASITES. 



like^ margins and radiating fibres; the oesophagus was short and 

 narrow, and soon passed into the nearly uniform intestine, which 

 was bifurcated a little above the central sucking disc, and ran 

 down on each side of this towards the caudal extremity, where, 

 being covered by the ovaries, it could be traced no further. 

 The ovaries were indistinct, and their cotyledons appeared to 

 be arranged irregularly transversely." 



Such is the account given by Gescheidt in his memoir (Von 

 Ammon's ' Zeitschrift/ iii, No. 4). Von Ammon, who has in 

 vain endeavoured to find the preparations referred to in the 

 Pathological Collection of the Academy of Dresden, in order to 

 send them to me, has represented these Distoma in his fine 

 work upon the congenital defects of the human eye, from which 

 the figures are copied. l 



B. NEMATELMIA=NEMATOIDEA=THREAD-WORMS or ROUND- 

 WORMS. 



General Part. 



The worms here to be treated of were referred to by Rudolph! 

 as Order I, " Nematoidea ; corpore elongato, tereti, elastico ;" but 

 by Diesing, in his ' Systema/ as Sub-class I, Achathelmintha ; 

 Section n, Ach. elastica ; Order VI, Nemaloidea, and described 

 in the following terms : " Corpus elasticum, cavum, subcylindricum ; 

 tractus cibarius simplex ; caput in proboscidem hand protractile. 

 Endoparasita, tandem rarius extus libere vagantia" 



We make use of the name NEMATELMIA here, in order to 

 maintain a greater uniformity for the two divisions. 



Corpus teres, elasticum, scspe attenuatum, Jiliforme, ore centrali 

 vel subcentrali ; canalis cibarius aut distinctus, aut obsoletus, anoque 

 destitutus. Metamorphosis in paucissimis. Migrationes actives 

 aut passives in permultis. 



In the human subject we meet with the mature Nematode 

 worms, partly in open cavities of the body furnished with mucous 

 membranes (intestinal canal, lungs, kidneys, &c.) ; partly in the 

 subcutaneous cellular tissue, with an artificial external communi- 

 cation ; and lastly, during their youth and in an immature state, 

 encysted in very various muscles, especially primitive muscular 

 fasciculi. The study of the individual worms belonging to this 



) See Appendix B. 



