3G2 Miscellaneous. 



taken as the subject of his dissections some largo tropical species, 

 and he has veriticd the exactness of the results obtained in the Gor- 

 d'ms suhhifarcnn of Europe. 



\ye may distinf!:uish, -with M. Schneider, in the skin of all the true 

 Nematodes, two layers — the one internal and cellidar, Mng directly 

 on the muscles, called the subcutaneous layer, and the other external, 

 the cuticle, secreted by the first. The two layers occur in exactly 

 the same way among the Gordiacea ; but M. Meissner entirely mis- 

 understood their nature. He considered the subcutaneous layer as 

 being in direct relation with the muscular system, and gave it the 

 name of perimysium. As to the ci;ticle, it is formed of two laminoe, 

 of which the innermost was regarded by M. Meissner as a fibrillar 

 corium, and the external as an epidermis of cellular nature. 



In immediate dependence upon the skin is the organ which M. 

 Meissner has described as a ventral nervous cord. M. Schneider was 

 afterwards better inspired in regarding tliis cord as the homologue of 

 the ventral line of the Nematodes. Nevertheless, in his monograph 

 of the Nematodes, he abandons this opinion and regards the cord in 

 question as an oesophagus deprived of all communication with the 

 intestine — that is to say, as the morphological equivalent of an oeso- 

 phagus, not fidfilling the functions generally supposed to belong to 

 that part. It docs not, indeed, present any mouth in front, or any 

 communication with the intestine behind. This interpretation is 

 energetically opposed by M. Grenacher. This observer recurs to the 

 first idea of M. Schneider, and regards the supposed nervous cord as 

 homologous with the ventral line of the Nematodes. He shows be- 

 sides, by means of a series of very convincing sections, that this organ 

 is really an excrescence of the subcutaneous layer. A narrow fissure 

 of the muscular cylinder along the ventral line permits a lamina to 

 pass, which establishes the continuity of the tissue between the sub- 

 cutaneous layer and the ventral cord. 



The muscular system of the body of Gordiiis forms in the interior 

 of the subcutaneous layer a cylindrical layer, interrupted only along 

 the ventral surface by the gap through which the ventral cord com- 

 municates with the subcutaneous layer. This cylinder is composed 

 of lamina?, which M. Schneider compares with the fibrillar of the 

 other Ncmatoda. M. Grenacher, on the contrary, regards each la- 

 mina as a muscular cell, homologous with those of the Polymyaria. 

 These larainte, indeed, are not solid, but each constitutes a tube, 

 though, it is true, of very smaU calibre. The calibre is directly com- 

 parable to the medullary mass of the muscles in the other Neniatoda. 

 The author has not, however, succeeded in finding the nucleus of 

 these muscular cells. 



The tube formed by the different layers of the body-wall that we 

 have just described is filled Avith a cellular tissue, in which the other 

 organs are immersed. This tissue is designated by ^f. (Jrenacher the 

 perienteric connective suhslance. It is to it that M. ileissner, by a 

 curious inter])relation, ascribed the function of an intestinal canal. 

 H(! assumed, in fact, that the mouth h'd directly into tlu> cavity filled 

 l)y tliis tissue ; so that the genital organs would liave been lodged in 



