unit Fertilization in the Nematoidea. J 77 



intestine of Triton taniains, &c. Sometimes \vc have found the 

 posterior extremity of the germ-stock very considerably thickened 

 also in Ascaris mystax. 



This structureless tunica projnia is chjthed upon the surface 

 turned towards the lumen with an epithelium, as has already 

 been described by Lieberkiihn, Schneider, and Meissner in 

 various Nematoidea. In most sj)ecies this e])ithelium is very 

 distinct in the vagina and uterus ; its detection is more diflicult 

 in the oviduct and vitellogcne. In the upper part of the latter 

 and in the germ-stock we have been unable to discover an ej)i- 

 thelial coat in any single Nematoid worm. Lieberkiihn, also, 

 who has accurately described the distribution of the epithelium 

 in a worm from the proventriculus of FuUca atra and Anqs 

 Boschas domestical, has never been able to trace it to the upper- 

 most part of the sexual tube. 



In one species of Ascaris we have met with a form of c])ithe- 

 lium, which, at the first glance, appeared to be in favour of 

 Bischoff, in his dispute with Nelson and Meissner. This is the 

 Ascaris suilla, from the intestine of the Pig. In this Ascaris 

 the uteri as well as the oviducts are lined with large epithelial 

 cells, 0*10 to 0"18 millim. in breadth, each of which is furnished 

 with a process of 0"018 to 0'027 millim. in length, which pro- 

 jects into the lumen of the tube. The process is about as bro;ul 

 as long. It cannot be denied that there is a considerable re- 

 semblance between these processes and Bischofl's epithelial 

 conules, except that the former are a good deal larger. But the 

 Ascaris of the Pig is considerably larger than that of the Cat. 

 The processes and conules, howcvei-, differ from each other in 

 many respects. The latter only adhere very loosely to the wall 

 of the genital tube, whilst the former are tirmly attached to the 

 epithelial cells ; they are formed by a prolongation of the cell- 

 membrane, and cannot be stripped off in any way. Most of 

 Bischoff's epithelial conules are found free in the tube oi Ascaris 

 mystax, in consequence, we are told, of the weakness of the 

 original union. But we could not succeed in separating the 

 processes of Ascaris suilla from their foundation. Lastly, we 

 have to mention one circumstance which sufficiently proves that 

 the processes and conules have nothing to do with each other. 

 In certain female individuals of Ascaris suilla, — and indeed, as 

 we shall see hereafter, in the unfecundated individuals, — not only 

 the processes of the epithelial cells, but also Bischoff's epithelial 

 conules occur. The latter arc considerably smaller than the 

 processes, and it was impossible to detect any relation between 

 them and the ej)ithelium. 



Meissner has already mentioned a villous epithelium ni Ascaris 

 * Beitriige zur Anatomic der Ncniatodeu. Muller's Archiv, 185.5. 

 Ann. eV Mag. N. Hist. Ser. 3. Vol. i. 12 



