570 DE. H. CHAELTON BASTIAN ON THE ANATOMY AND PHYSIOLOGY 



principal roots, though in what precise manner could not be detected, owing to these 

 parts being obscured by the dense fibrous raeshwork which extends for some distance 

 in front of the ring, as well as over much of the space between this and the head. The 

 fibres composing this network are in part, undoubtedly, connecting nerve-fibres, though 

 the greater portion of the tissue seems to be composed of mere protecting fibres, pro- 

 bably derived from the muscles. Near the origin of these ventral nerd sul/mediani, on 

 either side, between them and the lateral tracts, are two small but distinct bipolar gan- 

 glion-cells (k, k), one fibre of which seems to come from the oesophageal ring, whilst the 

 other connects the cell vaih. one of the nerves in question. The dorsal nervi submediani 

 (i, i) seemed to me principally derived from the ganglion-cells in the lateral tract poste- 

 rior to the oesophageal ring, and appeared to curve gently upwards to supply the upper 

 cephalic lobe. This lobe seemed also to derive fibres from two large nucleated ganglion- 

 cells*, one of which is situated just external to each lateral tract {h, h), and also a small 

 bundle of fibres from the nervi laterales. Although nei-ve-fibres have been detected only 

 in the anterior part of the body of A. lumhricoides and other Nematoids, I have not the 

 slightest doubt that peripheral branches do exist throughout the body generally ; and 

 from what I have seen of the course of one large fibre proceeding backwards from one 

 of the lateral ganglion-cells, I suspect that they generally pass beneath the muscles to 

 gain the deep cellular layer of the integument, in which they are principally distributed, 

 and from which they can so easily give off filaments to the muscles or to tactile papillae. 

 I distinctly saw a fibre (marked e) leaving the substance of the lateral cord and passing 

 beneath the muscular bundle lying outside it. Dr. Schneidee seems inclined to think 

 that some large nerve-fibres may pass posteriorly in the substance of the dorsal and 

 ventral median lines, though he has never absolutely traced nerve-fibres passing from the 

 central ring into these bodies. He rests his opinion upon the fact that in fine transverse 

 sections which he has made of the median lines, he has found them perforated length- 

 wise by cavities having an elliptical or oval cross section; which tubes or cavities, he 

 states, are invariably filled with a transparent, homogeneous substance of a reddish or 

 yellowish tint. He says that from six to eight such bodies can be detected in the 

 ventral median line of A. megalocephala, but only from four to six in the dorsal. These 

 are considered to be transverse sections of nerve-fibres ; but the fact that they have a 

 distinctly lai'ger diameter than the principal nerve-fibres issuing from the ganglion-cells 

 seems to me strongly opposed to this view. I have myself been imable to recognize 

 such structures in the median lines, so must refer for further details concerning them to 

 Dr. Schneider's important memoir. 



The nervous system of Oxyuris curvula has also been carefully examined by Schneider, 

 and in this animal he has found the oesophageal band most distinct, as well as the ante- 

 rior fibres, though very few ganglion-cells could be detected. He has with difficulty, 

 moreover, detected the most important parts of this nervous system in Strwigylus 



* These large cells have rather a remarkable appearance from their isolated position, but still the aspect of 

 their nucleus and ceU-contents corresponds most closely with that of other ganglion-eeUs. 



