134 



ENTOZOA. 



Fig. 83. ovaries in the female and 

 testes in the male. They 

 are extremely minute at 

 their commencement, but 

 increase so as to be readily 

 visible in the middle of 

 their course. They are trans- 

 parent and irregularly dila- 

 ted or sacculated at inter- 

 vals. Posteriorly they ter- 

 minate in a cul-de-sac, and 

 have no anal outlet. They 

 contain a transparent in- 

 odorous albuminous liquid, 

 give off no visible lateral 

 branches, and do not com- 

 municate together in any 

 part of their course. Be- 

 sides these canals we find 

 in the cavity of the body 

 of an Echinorhynchus two 

 long wavy tubes called 

 lemnisci, (d, d, fig. 83). 

 They are attached to the 

 lateral parts of the neck by 

 an extremely attenuated an- 

 terior extremity, float freely 

 in the remainder of their 

 extent, and terminate in an 

 enlarged obtuse and imper- 

 forate extremity. They are 

 of a whitish colour, tran- 

 sparent in the living worm, 

 but become opake after 

 death; they present consi- 

 derable variety of form, and 

 would seem to be highly 

 irritable parts, since they are 

 not unfrequently found fold- 

 ed into a packet, or twisted 

 both together, and, turned 

 to one side of the body. 

 When examined with a high 

 microscopic power, a tran- 

 sparent vessel is perceived 

 running through the centre 

 and ramifying as it descends 

 in the substance of the lena- 

 niscus, which is soft, fragile, 

 and granular. Cloquet com- 

 pares these organs to the 

 nutrient processes which 

 project into the abdominal 

 cavity of the Ascaris, and 

 they are also regarded by 

 Goeze, Zeder,and Rudolphi 

 as belonging to the organs 

 of nutrition. 



In the Ccelelmintha or 

 Cavitary Entozoa, the ali- 

 mentary canal is single and of large size, and 

 extends nearly in a straight line from the mouth 

 to the anus, which are at opposite extremities 

 of the body. With regard to the existence of an 

 anal outlet, the parasitic Entozoon, ( Syngamus 

 tracftcalis, Siebold,) which infests the windpipe 

 of our common Gallinaceous Birds, presents an 

 exception. It was suppored by Montague to be 

 a single individual with two pedunculate mouths : 



Digestive and gene- 

 rative organs, Echi- 

 norhynchus gigas, 

 female. 



Transverse section of Echinorhynchus gigas. 



and by Rudolphi was placed in the same group 

 as Distomafurcatum, which is a true double- 

 necked Trematode worm. But the digestive 

 system has the essential character of the ccelel- 

 minthic structure, the intestine floating freely 

 in an abdominal cavity. The orifice at the 

 extremity of the smaller or male branch leads 

 to a muscular oesophagus, which is continuous 

 with a somewhat broader reddish-brown intes- 

 tine, continued in a tortuous manner down the 

 neck, and terminating in a eu!-de-sac prior to 

 the confluence of the extremity of this branch 

 with the body of the female. The mouth of 

 the larger branch, which is the true continua- 

 tion of the larger and single body, leads first 

 to a horny basin-like cavity, which communi- 

 cates by an opposite pore, surrounded by six 

 horny hooks or teeth, with the oesophagus, 

 from which a similar reddish-brown intestine 

 is continued, but in a more tortuous manner 

 than in the male, through the whole body, ter- 

 minating in a cul-de-sac at the caudal extre- 

 mity. In both intestinal canals are molecules 

 of apparently the colouring matter of blood. 

 Their inner surface is reticulate. 



In the freedom of these intestines from the 

 muscular parietes of the body, and in the cy- 

 lindrical form of the latter, we have a close 

 affinity to the Nematoid type: but the intestine 

 is blind without an anal outlet. It is not, 

 however, bifurcate, as in the true Trematoda. 



In the genus Lingua tula or Pentastoma of 

 Rudolphi, the intestine is a simple straight 

 tube, and is surrounded by the convolutions 

 of the oviduct : the two intestinula caca with 

 which Rudolphi describes the alimentary canal 

 as being complicated,* appertain to the gene- 

 rative system, and communicate exclusively 

 with the oviduct : the intestine terminates by 

 a distinct anus at the posterior extremity of 

 the body. 



In the Nematoidea the intestine is also 

 frequently concealed in a part of its extent by 

 the coils of the genital tubes, but these are 

 disposed in masses by the side of the alimen- 

 tary canal, and not wound around it as in the 

 Linguatula : in most species the alimentary 

 canal is attached to the internal parietes of the 

 abdominal cavity by means of numerous small 

 laminated or filamentary processes. 



In the Strongyha gigas the mouth (A., fig. 

 71) is surrounded by six papillae; the cesopha- 



* Synopsis Entoz. p. 584. 



