666 DB. H. CHAELTON BASTIAN ON THE ANATOMY AND PHYSIOLOGY 



the smaller dorsal and ventral cords of a similar nature in A. lumbricoides have been 

 described as nerves by Otto * and CLOQUETf . The foimer also described a ventral cord 

 in Strongylus gigas, giving off a few transverse branches in its course and ending at either 

 extremity of the body in a terminal swelling. OwenJ desci-ibes a somewhat similar 

 structure in this animal, but adds that it commences and ends with slender nervous rings 

 around the anterior portion of the oesophagus and the anus respectively. From the 

 description given by him of this ventral cord, and the disposition of its branches, one is 

 led strongly to believe that it in reality corresponds to the ventral median line with its 

 attached transverse muscular processes ; although Siebold § distinctly states his belief that 

 the ventral cord seen in Strongylus gigas is of a different nature from that met with in A. 

 lumbricoides and other Nematoids, and adds as a description of a structure then before 

 him, " Dans son trajet il envoie une multitude innombrable de filets lateraux, qui par 

 leur structure in time, different essentiellement des faisceaux musculaires transversaux." 

 Professor Owes affirms, however, that this ventral cord passes " to the left side of 

 the vulva, and does not divide to give passage to the termination of the vagina, as 

 Cloquet describes the corresponding ventral cord to do in Ascaris lumbricoides." He 

 agrees with Otto in the statement that only a ventral cord exists in this animal, though 

 Blanchakd suggests that this may have been a mistake, owing to the destruction of the 

 dorsal cord by the section of the body of the animal in the mid-dorsal region. Blanchard || 

 also considers the dorsal and ventral lines to be the extremely developed peripheral portions 

 of the nervous system in the Nematoids. He says that in all the representatives of the 

 order he has found " une disposition tout-a-fait semblable dans I'appareil de la sensibilite," 

 which he describes in these words : — " le corps place dans la position oii les deux nerfs 

 principaux^ se trouvent etre lateraux, on observe de chaque cote de I'cEsophage deux 

 tres-petites masses medullaires placees exactement sur le meme plan, et unie a ceUes du 

 cote oppose par une double commissure extremement grele, I'une passant alors au-dessus 

 de I'cesophage et I'autre au-dessous." In the Ascarides and Filarioe these ganglia are, 

 he says, double on each side, but in the Sclerostomata they become fused into one. 

 Nothing answering to this description has been met with by other observers, and the same 

 must be said of the double nervous cord figured and described by Professor Grajs'T** 

 as traversing the ventral region of the body in Ascaris lumbricoides. 



MEissNEEf f described the transverse muscular processes in the Gordiacece as branches 

 of a peripheral nervous system, and put the same interpretation upon the homologous 

 prolongations in the Nematoidea ; and at one time HuxleyJ;}; seemed inclined to assent 

 to the same view of the nature of these transverse muscles in the Nematoids. Waltee§§ 

 formerly described a most elaborate system of nervous ganglia and cells with peri- 



• Magaz. d. Gesell. Nat. Fr. Berlin, vii. 1814. f Sur les Vers Intestinaiix, 1824, p. 23. 



t Cyclop, of Anat. and Phys. vol. ii. p. 130. § Man. d'Anat. Comp. (Trad. Frang.) p. 126, note. 



11 Ann. des Sc. Naturelles, 3"^ ser. 1847, p. 124. % Dorsal and ventral median lines. 



** Outlines of Comp. Anat. p. 186, fig. 82 A. tt MUllee's Archiv. 



%X Lecture in Med. Times, 1856, vol. ii. p. 384. §§ Zeitschr. fur Wissensch. Zoolog. 1857. 



