594 DR. H. CHARLTON BA8TIAN ON THE ANATOMY AND PHYSIOLOGY 



an outgoing tube from a vascular arch formed from lateral vessels as in A. megaloce- 

 phala, since the tube is here more than twice as broad as the whole lateral band (Plate 

 XXII. fig. 10, a, h). I am sorry I had neither time nor specimens sufficient to examine 

 this animal more fully. Walter has described the lateral bands of Oxyuris vermicularis 

 as closely resembling those of Ascaris lumbricaides, and like them containing an axial 

 vessel; but then Walter differs in so very many points from other observers, not 

 only as regards the actual presence or absence of certain structures, but also as regards 

 the interpretation of others well known and recognized to exist, that it would be desi- 

 rable to have this observation verified by some other investigator. Schneider has been 

 quite unable to discover the usual anterior ventral pore in this animal, neither have I, 

 after the most careful search, been able to find it ; and, notwithstanding the transparency 

 of the animal, I certainly never could discover any trace of an axial vessel contained in 

 the lateral bands. In Oxyuris spirotheca, moreover, Schneider has equally faUed to 

 discover a vessel within the lateral band ; according to him it is made up solely of the 

 usual admixture of granules and cells. The lateral bands of three species of the genus 

 Strongylus have been described by Eberth. In S. tenuis and S. commutatus he says 

 may be seen the simplest condition of the lateral lines ; in the former they consist each 

 of a simple row of small cells, such as may be seen in many of the Trichosomata ; in 

 S. commutatus also the lateral lines are narrow and made up of small cells, whilst in this 

 animal Ebeetii also reports the presence of a double ventral gland. He states, however, 

 that a different structure is met vdth in S. striatus, the lateral band being well developed, 

 containing granular matter and nuclei, and also a delicate axial vessel ; but in this species 

 he does not seem to have certainly detected a ventral gland ; he speaks of two organs, 

 indeed, within the ca\ity of the body, though he also states that these seemed to be 

 prolongations from the oesophagus, and that he was unable to recognize any external 

 orifice. The organization of this animal must therefore be considered as still doubtful. 

 Ebeetii seems to have examined the Trichocephali and Trichosomata much more fully 

 than any other observer, and he makes no mention of the existence in them either of 

 any modification of the ventral gland, or of vessels contained within the lateral bands. 

 The structure of the longitudinal bands, both lateral and median, is of two principal 

 kinds in these animals; and although they present the greatest variety as regards 

 arrangement and relative size in different species, their actual histological structure 

 is almost uniform throughout the whole group. He describes the simplest form as 

 consisting of a long string of small cells or nuclei, which may either form a single 

 row occupying the whole breadth of the band, or when the band is larger lie in con- 

 tiguous rows, the several cells of which are separated from one another by a finely gra- 

 nular material*. The size of the single cells is variable; and whilst the smaller ones 

 contain only a minute punctiform nucleus, the larger are beautiful polygonal bodies, 



* In connexion with this structure of the lateral band it will be well to notice also what Ebebth says of the 

 so-called granular layers in these animals. His words are, " Dicht unter der Haut triflft man eine zarte 

 ieinkomige Schicht, die mir aus sehr zarten Zellen zu bestehen scheint." — Unters. iiber Xemat. p. 46. 



