660 DE. H. CHAEI^TON BASTIAN ON THE ANATOMI AND PHYSIOLOGY 



These transverse fibres, such as are alluded to by Siebold, have been looked upon as 

 vessels by Bojanus*, Cloquet, DiESiNGf, WaltebJ and others, whilst they were sug- 

 gested by Meissneb§ to be branches of the peripheral nerve-trunks, similar to what he 

 erroneously considered to be the nature of homologous processes in the Gordiacea;. 

 Schneider and Eberth, as well as myself, are quite agreed as to the nature of the trans- 

 verse fibres described by Siebold, and in speaking of the histology of the muscles, I 

 shall fully describe their origin and distribution. 



In addition to these principal muscles extending through the body generally, there 

 are other smaller local fasciculi, some common to both sexes, for the opening and closure 

 of the anal cleft, whilst others are peculiar to the male. They are, besides bundles for 

 the protrusion and retraction of the spiculi, a series of fibres — always well marked in 

 the genus Ascaris — extending on each side, for some distance above the ano-genital 

 opening, from the lateral bands to the mid-ventral region and median line (Plate XXIII. 

 figs. 3 & 4). These are most developed, and constitute gradually thicker bundles poste- 

 riorly. In A. osculata they attain an enormous development, and separate the longi- 

 tudinal muscles into three nearly equal bands || , their extremities completely obliterating 

 and occupying the place of the mid-ventral and lateral lines (Plate XXVI. fig. 12). In 

 A. lumbricoides these peculiar fibres may be met with in the males for about a distance 

 of 1^" from the posterior extremity of the body, so that the extent of their distribution 

 corresponds exactly with that of the ventral papillae before described ; which leads me 

 to believe them to be destined to flatten the ventral region of the male, and so enable 

 the papillae, whether suctorial or simply tactile, to be brought into contact with the 

 body of the female when the posterior extremity of the body of the male is coiled round 

 it in actu coitus. 



The bands of longitudinal muscles vary much in thickness in different species ; they 

 are much more developed, for instance, in A. megalocephala than in A. limibricoides, 

 and in the males, of all species of Ascaris at least, form much thicker bands than in the 

 females. In the male the cavity of the body frequently becomes much diminished, 

 owing to the encroachment upon its area by the four thick convex longitudinal masses 

 of muscle. 



We are indebted to Dr. Schneider^ for a most accurate account of the histological 

 structure of the muscles in the Nematoids, and though his views have been questioned 



* Isis, 1821, p. 187. pi. iii. figs. 51 & 54. 



t Annal. d. Wiener Mus. ii. part 2, pi. xvi. fig. 1, et pi. xviii. fig. 2. 



t ViKCHOw's Archiv, 1862, Bd. xxiv. p. 166. Taf. iii. 



§ MUllee's Archiv, 1856. 



I! These three bands are produced in this manner : — in the male Nematoids, towards the posterior extremity 

 the lateral lines deviate from their median position and run closer to the dorsal surface. Here also the dorsal 

 median line is often wanting, and the two diminished dorsal muscles blend into one band, about equal in size 

 to each of the ventral longitudinal muscles, and so produce an arrangement similar to what Meissnes has 

 described as generally existing in the genus Mermis. 



f MtLLEB's Archiv, 1860, S. 224. 



