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



mental pore as the essential portion of the structure, and have never considered them 

 to be tactile papillae. This impression regarding their nature is rendered even more 

 probable by what we see in Prosthecosacter inflexus (Plate XXVII. figs. 1 & 2). 

 It seems, moreover, difficult to imagine what could be the use of papillae in these 

 situations, though it does appear to be a pretty constant rule amongst the Nematoids 

 for the deep cellular layer of the integument to communicate with the exterior by 

 means of channels through the chitinous envelope. No fine integumental pores, 

 such as we have hitherto described, exist in the majority of the parasitic Nematoids, 

 but so far as we have examined, both Ebebth, Schneider, and myself have found 

 in these animals the larger cervical and caudal openings. May they not be looked 

 upon as in a measure substitutes for one another 1 This opinion is also supported by 

 the fact that the surface-depression into which they open is occasionally so marked as 

 to discountenance the idea that they are to be looked upon as papillae. The view 

 entertained by Ebekth, that these pores are openings of the water-vascular system, I 

 have no hesitation in believing to be erroneous. Schneider also is quite opposed to 

 this interpretation of their function. After repeated examinations I have quite satis- 

 fied myself that, though situated externally to the lateral bands, these integumental 

 channels have no communication with the longitudinal vessels often contained within 

 them. Such pores exist on each side of the cervical region of Ascaris osculata, though 

 vessels are present only on the left side (Plate XXVI. fig. 9) ; and again, in Cucullanus 

 heterochrous, the caudal pores are distinctly posterior to the csecal terminations of the 

 lateral vessels* (Plate XXVII. fig. 12, a & b). 



In Ascaris lumbricoides, in addition to the papillae already described as existing on its 

 cephalic lobes, I have detected certain integumental channels of two kinds; the first 

 being two in number, and situated one on each side on the latero-ventral lobe, near its 

 upper border and anterior to the level of the larger central papilla (Plate XXII, figs. 14 

 & 19, c). At these points the cellulo-granular layer is formed into a conical projection 

 which reaches the surface at a slight depression in the chitinous envelope (Plate XXII. 

 fig. 18, c, d), and communicates with the exterior by means of a small circular aperture. 

 The other channels (two on the anterior border of each lobe) are very minute, and are 

 mere capillary passages through the thick chitine in this situation (Plate XXII. figs. 18 

 & 19, e, e), with no apparent projection of the cellular layer beneath. In all probability 

 both these kinds of channels are to be met with in the cephalic lobes of other Ascarides. 



* In a species of Dispharagus, from the gizzard of Colymhus septentrionalis, I found the caudal openings, 

 though I could not recognize the cervical. I did find, however, in this region, on each side of the body, a pro- 

 jection of the chitinous integument (Plate XXII. fig. 1). KtCHEifMEisTER represents lateral cervical projection.s 

 of this kind also in Anchylostomum duodenale, and I have likewise seen them in a red-coloured Strongylus from 

 the stomach of a hare. I was, however, unable to recognize perforations through these structures. In the 

 females of the last-mentioned animal also the two caudal pores seemed to be replaced by a large number of 

 integumental channels distributed over the whole circumference of this region of the body ; though in the 

 males two well-marked lateral pores were visible just above the level of the bursal expansions. They are very 

 long, on account of the thickness of the integument in this region. 



