KNTO/OA. 



1:11 



iirpiins. We have idroady alluded 

 to the tc> leading modifications uf tlie ali- 

 mentary canal, mi which llic Unary division 

 of tlic Kiitci/oa of Rudolphi is founded, viz. 

 into Sterebmntha or thuse in which the nu- 

 trient tulies, without anal outlet, are simply 

 cvaiatcd in the. ucncral parcin liyma, and into 

 the Cii/i'/ininl/iH, in which an intestinal canal, 

 with |iro|ic-r panetcs, floats in a distinct ab- 

 ilonunal cavity, and has a separate outlet for 

 tin- excrements. In both these divisions the 

 mouth is variously modified, so as to aflbrd 

 zoological characters for the subordinate 

 groups; and the alimentary canal itself in 

 the Slerelmintha presents several important 

 differences of structure. 



Ci/sticit. The Cystic worms are generally 

 Kitted, as in the species fCyticercta ceUatoif) 

 which occasionally infests the human subject, 

 with an uncinated proboscis for adhering to and 

 irritating, and four suctorious mouths for ab- 

 sorbing the fluid secreted by, the adventitious 

 cyst in which they are lodged. In the larger 

 t'l/xticerri lateral canals may be traced from the 

 suctorious pores extending down the body 

 towards the terminal cyst, but they appear 

 not to terminate in that cavity, the fluid of 

 which is more probably the result of secretion 

 or endosmosis. We cannot, however, partici- 

 pate in the opinion of Rudolphi,* that the 

 retracted head derives nutriment from the 

 .surrounding fluid of the caudal vesicle, for if 

 that were the case, where would be the neces- 

 sity lor an armed rostellum in addition to 

 tin alisiuhent pores? The frequency with 

 "Inch the Cysticerci are found with the head 

 si i retracted, may be attributed to the in- 

 stinctive action arising from the stimulus of 

 diminished temperature and other changes 

 in the surrounding parts occasioned by the 

 death of the animal in which the hydatid 

 has been developed. 



Cistiiidea. In the Cextoidea the digestive 

 apparatus commences for the most part by two 

 or four oral apertures, to which, in many spe- 

 cies (the Ticniie armuttt), a central uncinated 

 proboscis is supcradded, as in the Cysticerci. 

 Sometimes the months are in the form of oblong 

 pits or fossae, as in the Hothrioccphulus hit us, and 

 the allied species grouped under the same gene- 

 ric name ; or they have the structure of circular 

 suctorious discs, as in the Tifniu snliiim and 

 Other true Tieni/e.\ In both genera two alimen- 

 tary canals are continued backwards in a straight 

 line near the lateral margins of the body (e, e, 



" Osculis tamen canalihusque dictis omncm 

 a(jii;i vim vi-sira caudali collectam parari pcluissi- 

 vi\ rrt'uibile, sed hac parata vermrm camlrin 

 absorbere ideoque semper ferecuput huic iminissum 

 offerre, longe aliam vero fluidi advehendi vi.im 

 dari. plnrima suadrnt." Hist. Entoz. i. p. 279. 



t Many bcantilul preparations, showing the 

 nutrient canals of the Ta-nia tolium injected with 

 coloured size and <|uickMlver, are preserved in the 

 Hnnterian collecium, (see Nos. 843, 844, 845.) 

 These were prepared, during the lite-time of John 

 Hunter, and were presented to that great auato- 

 inUi by Sir Anthony Cailisle, by whom they are 

 dt'M'ritjed in the Observations upon the Strtic- 

 tun- and (Economy of T<enia-,' in the second vo- 

 lume of the Linnxan Transactions, (1794). 



H), and are united by Iransvcrst canals 

 I t.J,tiL'. '," , lossthcposlriior i 



of (hi: segments. These cunnci'tin-j HD 

 relatively wider in the Ttnia nnliiuii tlian in the 

 1-fot/ininTiilinln.-. latits, tlieir size apparently 

 depending on the length of the segments, 

 which is much greater in the former than the 

 latter. Neither tlie transverse nor the longi- 

 tudinal vessels undergo any partial dilatations. 

 The chief point at issue resecting the digestive 

 organs of the Tape-worms is, whether the nu- 

 triment is imbibed by them through the pores 

 which occur at the sides or margins of eacli 

 joint, or whether the entire body is dependent 

 for its nutriment upon the anterior mouths from 

 which the lateral canals commence. The re- 

 sults of numerous examinations, which I have 

 made with this view, both on Hothriocepliali' 

 and Twniffi, have uniformly corresponded with 

 those of Rudolphi, and I entirely subscribe to 

 the opinion of that experienced helminthologist, 

 that the marginal or lateral orifices of the seg- 

 ments are exclusively the outlets of the gene- 

 rative organs. 



In some species of Tape-worm, as the 'ftenia 

 sp/iieniictpfialus, in which no ovaria have been 

 detected, there has been a corresponding ab- 

 sence both of lateral and marginal pores, while 

 the lateral longitudinal canals have been pre- 

 sent and of the ordinary size. In the Tttnia 

 solium the generative pores being placed at 

 one or other of the lateral margins of the seg- 

 ments, the ducts of the ovary and testis (g, h, 

 Jig. 90) cross the longitudinal canal of that 

 side, and give rise to a deceptive appearance, 

 as if a short tube were continued from the 

 alimentary canal to the pore. Hut in the 

 Buthriocep/ialus lutus and Bolliriucephalut 

 Pythonis the generative pores open upon the 

 middle of one of the surfaces of each segment, 

 and in these it is plain that the lateral nu- 

 trient vessels have no communication with 

 the central pores. The orifices of the segments, 

 in short, correspond with the modifications of 

 the generative apparatus, while the nutrient 

 canals undergo no corresponding change. 

 Nutrition may be assisted by superficial ab- 

 sorption ; and, as Rudolphi suggests.-f the se- 

 parated segments may for a short time imbibe 

 nutriment by the open orifices of the broken 

 canals ; but setting aside cutaneous absorption 

 and the more problematical action of the rup- 



* Principally on that species which infeits the 

 intestines of the large serpent commonly exhibited 

 in this country the Python Tigrit, Dand. And we 

 invite the attention of comparative anatomist* 

 interested in this point to an injected preparation 

 of one of these worms in the Museum of the Royal 

 College of Surgeons, No. 84S A. 



t " Al. Offers (de veget. et anim. p. 35) 

 articulos Trrnia- singulos ope absorptionis cutanez 

 perparum, maxinic autem ope osculi marginahs 

 nutriri contendit, sed osculum hoc vcre ad genitalia 

 pertinere in capitc insequente evincam. Si cl. 

 vir absorptionem culanram minoris xxlumat, hac 

 de re non litigabo, sed res alio modo rxplicari 

 potest. Annon enim ad vasa linearia nutneniia. 

 utrinque longitudinaliter decurrcntia, si anim .us 

 solu'us pst, in utroque ejus fine utrinque hiantia. 

 absorhendi officium deferri posset." Synnpi. Ento*. 

 p. 585. 



