11G 



THE HELMINTIIES. 



§in. 



the peristaltic actions of the body and the alternate retraction and pro- 

 traction of the proboscis.'" 



In the Gordiacei, and Nematodes, no vascular system has as yet been 

 found. Only in a group of species described as Filaria phcium, has there 

 been foutid a riband-like organ concealed in the cavity of the body, and 

 traversed by a net-work of canals, which resemble those of the lemnisci of 

 the Acanthocephali.'"' 



§ 111- 



In the Cystici, Cestodes, and Trematodes, the vascular system is well 

 developed. Its canals have proper walls, the contraction of which pro- 

 duces the circulation. In the first two orders, it consists of two pairs of 

 longitudinal canals, which pass along the sides of the body and head, and 

 intercommunicate occasionally, by transverse canals. These four vessels 

 open, in the head, into an annular ring which surrounds the proboscideal 

 sheath; there is here, therefore, a completely isolated system.*'* In the 

 Trematodes, this system consists of a contractile net-work spread over 

 the whole body ; and in which are two larger trunks, which pass along 

 the sides of the neck and body.^-* 



5 Mehlis (Isis, 1801, p. 82) affirms to have seen 

 on the neck of Echinorhynchus ^igas two small 

 orifices by which the lemnisci open outwards. But 

 I hivve been unable to see them in this species, or 

 others of this same genus. If they really exist, 

 they will shed light upon the doubtful functions of 

 these organs. From what we know of their struc- 

 ture, it is not improbable that they belong to the 

 nutritive system, and transude a liquiil which 

 bathes and nourishes the organs in the cavity of 

 the body.* 



6 With the Nematodes, the liquid appears to 

 transude through the walls of the intestine into the 

 cavity of the body, and there bathe, without a vas- 

 cular system, all the organs. The riband-like organ 

 found in tlie Filaria piscium (see Wiesmann^s 

 Arch. 1838, I. p. 310), and which I have also found 

 m Ascaris oscu/ata, has the same vascular rami- 

 fications as the lemnisci of Echinorhynchus qi- 

 gas, and the vesicle-hke bodies are not wanting 

 upon the course of the prmcipal canal. Perhaps 

 they also transude the nutritive liquid, for I have 

 not found any communication between them and 

 the intestinal canal. 



The' two lateral enlargements also, which, as 

 already mentioned (§ 102), are extended between 

 the longitudinal muscles of the skin, have often 

 been regarded as sanguineous vessels ; but I have 

 observed with them neither longitudinal nor lateral 

 canals, t 



I These lateral vessels, regarded by some Hel- 

 minthologists as intestinal tubes, give off in their 

 course no lateral branches, except these transverse 

 canals. With the articulated Cestodes, these last 

 are always situated at the posterior extremity of 

 the articulations, thus giving a ladder-like aspect 

 to the entire vascular system. They are also 

 found, however, in Cnryophyllaeus mutabilis, 

 which is not articulated. 



Plntner {Muller^>s Arch. 1838, p. 572, Taf. 

 XIII. fig. 4, 5) affirms to have seen semilunar valves 

 at the orifices of the transverse canals of Taenia 

 solium. 



The four lateral cervical vessels which I have 

 observed not only in Taenia, but also in Bothrio- 

 cephalus, and Cysticercus, may be traced with 

 perfect distinctness in Taenia cyatliiformis, and 

 serrata, to the vascular ring which surrounds the 

 probtiscideal sheath. With CaryophyUaeus mu- 

 tabilis, and Taenia ocellata, which are without a 

 proboscis, this vascular ring does not exist any 

 more than with Bothriorephalus ; here also the 

 four lateral vessels widely ramify in the head, and 

 form by anastomoses, a distinct net-work. Botk- 

 riocephalus claviceps has a similar organization. 

 It should, moreover, be here observed that from 

 the contraction of its very thin walls the vascular 

 system will easily elude the observer. 



- The vessels of the Trematodes are remarkable 

 for their prominent flexures ; see Distomum cir- 

 rigerum, tcreticolle, duplicatum, and the various 

 species of Diplostomum (Nordmann Microgr. 

 Beitr. Uft. 1, Taf. II. fig. 8, IV. fig. 5, 6). One 

 should not confound with the sanguineous vessels, 

 as has often been done, the very finely-ramified 

 canals of the excretory organ, wliich will hereafter 

 be mentioned. Thus I think that the vascular 

 net-work of Distomum hepaticum described by 

 Bojanus (Isia,1820, p. 30.3, Taf. IV.) belongs to 

 this excretory organ. Laurer also (de Amphis- 

 tomo conico. p. 10, fig. 22), has not carefully dis- 

 tinguished them ; and Nordman?! appears to have 

 fallen into the same error (loc. cit.). 



With Diplostomum, the vessels open each side 

 into a large reservoir situated at the extremity of 

 the body. Between these two receptacles, the 

 excretory, organ passes to the extremity of the 

 body, and Nordmann has taken its orifice as 



* [ § 110, note .5.] The observations of JVest- 

 rumb and Burotv on the circulatory system of the 

 Acanthocephali, have recently been thoroughly 

 verified by Blanchard, who has illustrated it with 

 excellent figures ; see Ann. d. Sc. Nat. 1849, XII. 

 p. 21, and R^gne animal, nouv. Edit. Zoophytes, 

 PI. XXXV. fig. 2.— Ed. 



t [§ 110, note 6.] BerthoM (Ueber den Bau 

 des Was^erkalbes. &c. loc. cit.) has described a 

 vascular system with the Gordiacei; but Blanchard 

 (Ann. d. Sc. Nat. 1849, XII. p. 7) has faUed to 

 confirm his statements after very careful research. 

 — Ed. 



