578 DR. H. CHARLTON BASTIAN ON THE ANATOMY AND PHYSIOLOGY 



forwards, such as I have represented in Plate XXVII. fig. 14, c. It is often of a yellowish 

 colour, and sometimes no nucleus can be detected. KycnEXMEisTKE mentions these 

 bodies in his description of Trichocephalvs di»par, and Eberth says he has found them 

 in every species examined. For further details concerning the oesophagus and other 

 parts of the animals included in this division of the Nematoids, I must refer to Dr 

 Eberth's most interesting memoir and beautifully executed figures. 



Amongst the free Nematoids there are a large proportion of the species which do not 

 present a well-marked muscular oesophagus, and among them the best examples I can 

 cite are the members of the genera Phanoderma, Leptosomatum, Enoplus, Oncholaimus, 

 Chromadora, and Dorylaimus. I might name several other genera, but those just given 

 contain species of the largest kind, and are therefore best fitted for examination. In the 

 first five genera, which are marine, a quantity of pigment-granules are generally present, 

 more or less thickly interspersed in the substance of the oesophageal walls, and by 

 means of a rather thick section of the oesophageal region of the body of an Enopliis 

 communis I was enabled to ascertain that the oesophagus itself was cylindrical, and had 

 the characteristic triradiate lumen in its centre, and that moreover the olive-coloured 

 pigment was principally arranged along three longitudinal lines, corresponding closely 

 in position with the apices of these three radii. What, however, the exact histological 

 structure of the oesophageal walls may be I am unable to say ; in the genera above men- 

 tioned it certainly presents no well-marked granular cells, such as have been described in 

 the Trichocephali and allied animals. Eberth* also seems to have been much puzzled 

 by the structure of the oesophagus in some of these animals, and is able to throw but little 

 light upon the subject. In Phanoderma Cocksi and other members of the same genus, 

 there are three longitudinal rows of bright orange-coloured pigment-granules, and the 

 posterior widening half of the oesophagus is constricted at pretty regular intervals, so as 

 to give its borders a crenated appearance, very much resembling what we find in Trichina 

 spiralis and the Trichocephali. From the cut extremity of the oesophagus in Dorylaimus 

 stagnalis I have seen a number of small hyaline cells of varying size (Plate XXVII. 

 fig. 5) issue, but with this exception have never been able to detect well-marked 

 cells in the oesophageal walls of any of the free Nematoids. All that I have been 

 able to make out was a kind of clear, gelatinous, undifferentiated tissue containing in 

 its substance large, interspersed, pigment-granules. It is possible that this substance 

 may be a kind of contractile sarcode — at all events it seemed very consistent and some- 

 what elastic. In the various species of the genus Enoplus a number of bright lines or 

 linear spaces exist, having a transverse direction, though what the exact nature of these 

 structures may be I have been unable to ascertain. These cross stripings have also 

 attracted the attention of Eberth and BERLiKf . 



Judging from what I observed formerly of the structure of the oesophagus in the 

 Guineaworm, I should imagine that it must have been originally an organ with cellular 

 parietes, the disintegration of which would account for the quantity of granular matter 

 • Untersuch. iiber Nemat. 1863, p. 9. t Mullek's Archiv, 1853. 



