no 



TUE IIELMINTHES. 



<§. 104. 



The central nervous system of the Acanthocephali is very distinct. It is 

 always concealed at the bottom of the sheath of the proboscis, which this 

 last, being never in a state of complete rotraction. does not fill. It consists 

 of a dense mass of ganglionic, cellular globules blended together, and here 

 and there may be seen through the cell-mcmbranes their nuclei and corpus- 

 cles. This comparatively large mass sends off nerves in every direction, but 

 the tenuity of these prevents their being traced, especially after they have 

 entered the muscular walls of the proboscideal sheath.*^' 



With the Gordiacei,'"'* and Nematodes, a nervous system has been found 

 with certainty only in Slrongylus gigas. Here a cord arises from a swell- 

 ing in the head, traverses' the whole length of the body upon the median 

 ventral line, and terminates at the posterior end of the body in another 

 swelling;. It sends off in its course lateral filaments, thus resemblinjj the 

 nervous system of the Sipunculidae.*'^* 



< I have thus found the nervous system of the 

 Acanthocephali in Echinorhi/ncus ^ii^as, an^ua- 

 tatus, haeruca, and protetis. It can bj easily ob- 

 served by carefully pressing or tearing the probos- 

 cideal sheath. In thus tearing, you sametimes 

 completely expose the ganglionic mass with the 

 roots of the nerves. In no species that I have dis- 

 sected have I been able ti find the ganglionic ring 

 mentioned by Henle {Froriep^s neui Not. No. 

 2S5, p. 330, and Mailer's Arch. 1840, p. 31S) as 

 found about the genital orifice of Echinorhyncus 

 nodulosus. 



Dujerdin also (Hist. Nat. d. Helm. p. 435, 491, 

 PI. VII. fig. D. 4), has not observed it, but he dis- 

 tinctly perceived the central mass at the base of 

 the proboscis, and has figured and named it as un 

 corps glanduleux ou ganslionaire. 



5 As yet no nervous system has bsen found in 

 the Gordi;icei. Berthold (Uber den Bau des Gor- 

 dius aquaticus, 1842, p. 12) has be^n inclined to 

 regard as nerves two djlic.ite filaments which 

 traverse the c.ivity of the body of Gordius ; but, 

 as these give off no lateral branches, tliis opinion 

 cannot be admitted.* 



6 Many Helminthologists have erroneously taken 

 for nerves the delicate projecting lines which, situ- 



ated directly suVjcutaneous and often blended with 

 the skin, traverse the whole length of the body of 

 many Nematodes, and have been called the ventral 

 and dorsal lines. Their lattral branch 'S, as already 

 observed, are only transverse muscular bands. 

 Quite different from these is the louL'itulinal cord, 

 which Otto (Magaz. d. Gesellch. naturf. Freunde 

 zu Berlin, l^" Jahrg. 1816, p. 225, T.if. V.)has 

 described and figured as belonging to the nervous 

 system ; a view which I am disposad to adopt, in 

 spite of Nitzsch (Ersch and Gruber''s Eneyclop. 

 VI. 1821, p. 45) anj other Helminthologists. 



In a large female Stronsylus sisas, now undet 

 my eyas, there is a simple longitudinal c^rd beneath 

 the muscular envelope, and therefore in direct con- 

 nection with the skin, and which c.Uends along 

 the ventral surface. In its course it sends off 

 numberless lateral branches, which in their inti- 

 mate structure are quite different from the trans- 

 verse muscular bands. But neither here nor upon 

 the nerves of other worms have I ever seen the 

 enlargements spoken of by Otto. Grant's figure 

 of a djuble nervous filament traversing the body 

 of Ascaris is probably imaginary ; see Outlines of 

 Comp. Anat. p. 186, fig. 82, A. 



gus, whicli he regards as a brain ; these observa- 

 tions have since been confirmed by Van Beneden 

 (Ann. d. Sc. Nat. XI. 1843, p. 319), who, however, 

 regards this mass as belonging to the sympathetic 

 system. But, however viewed, an ojsophageal col- 

 lar has been distinctly made out, thus confirming 

 the views of Cuvier. 



In regard to the splanchnic system of nerves 

 with these animals, Kan Beneden (loc. cit.) de- 

 scribes it as consisting of two ganglia lying on the 

 oesophagus back of the oesophageal collar, and 

 from which pass off two filaments, which run along 

 the oesophagus, and enter the collar laterally. He 

 thinks tlie two ganglia are united by a transverse 



commissure. Further behind is another and larger 

 ganglion on each side, and from which pass off 

 filaments to the digestive cavity. See also my note 

 under § 93. — Ed. 



* [ § 101, note 5.] This view of Berthold is sup- 

 ported also by Blanchard (.\.nn. d. Sc. Nat. 1849, 

 XII. p. 6), who affirms that he has observed on 

 both sides of the body a double longitudinal cord, 

 which is usually very distinct. This, examined 

 microscopically, appeared to be composed like the 

 nerves of the other Helminthes. Blanchard, how- 

 ever, did not succeed in tracing these cords to any 

 cephalic centres. Nothhig of special value, there- 

 fore, is known on this subject. — Ed. 



