and Fertilization in the Nematoidea. 183 



the two authors who have studied the eggs of Cucullanus elegans 

 most in detail, namely KuUiker* and Gabriel f, do not say a 

 word about a rhachis. The Ijlind extremity of the tube of the 

 ovary in Cucu/hmus is filled with elcar vesicles, — the germinal 

 vesicles with their germinal spots. Between these vesicles there 

 is even there a transparent substance, by which they are enve- 

 loped. This is the first commencement of yelk-formation, and, 

 with a little attention, we may already distinguish delicate lines, 

 which bound the ovules. A distinction of germ-stock and vitel- 

 logene is therefore here practically quite impossible. That the 

 germinal vesicles are destitute of germinal spots in the upper 

 half of the ovary, as is asserted by Gabriel, is certainly not the 

 case. Tliis naturalist has even accused Bagge of error, because 

 he stated that he observed the germinal spots in the germ-stoek of 

 Strongylus auricularis and Ascaris acuminata. But any one may 

 easily convince himself of the correctness of Bagge's statement. 

 On the other hand, we have not been able to confirm Kolliker's 

 observation, according to which the germinal spots are produced 

 before the germinal vesicles themselves. 



As the eggs progress downwards in the genital tube, they 

 increase quickly in diameter in consequence of the rapid forma- 

 tion of the colourless transparent yelk : they then form a co- 

 herent mass. When an egg is torn away from this mass, it is 

 found to have a pyriform shape and a short thin stalk. By the 

 careful treatment of the mass of eggs with needles, or by gentle 

 pressure with the thin glass cover, the eggs ma}' not unfre- 

 quentl)'' be separated, so that we may perceive how they form an 

 elegant bunch. The bunch consists, as it were, of extremely 

 thin, delicate branches, and thick berries. In the axis of the 

 genital tube the little branches come together, and form a main 

 stem, the rhachis, which is here very thin. As this rhachis and 

 its branches are not only very delicate, but also, like the vitel- 

 line substance in Cucullanus elegans, colourless, they are not 

 always easily perceptible. They become so immediately, how- 

 ever, when the bunches of" eggs are coloured by solution of 

 iodine. 



We shall not speak here of those Nematoid worms in which 

 the vitellogene always contains only a single series of eggs, as 

 the egg-formation in these has already been sufficiently explained 

 by Siebold and Bagge. 



3. Formation of the Seminal Corpuscles. 

 With regard to the formation of the seminal corpuscles, we 



• hoc. cit. Muller's Archiv, 1843. 



t De Cucullani elegantis vivipari evolutione. Auctore Beuno Gabriel. 

 Berolini, 1S53. 



