FECUNDATION OF NEMATOIDA. 301 



the cell-wall of the germ-cell, and becoming affixed to the wall, 

 by which they drive out the cell-wall before them, and give the 

 germ-cell a biscuit-like tetrahedric form. The diverticula of the 

 cell-wail gradually becoming constricted around these daughter- 

 nuclei, the latter become independent development-cells of the 

 seminal corpuscles [brood-cells of the seminal corpuscles, according 

 to Reichert), like the mother-cell. Immediately after the con- 

 striction a small, strongly refractive nucleolar corpuscle appears 

 in the middle of the nucleus. The whole development-cell 

 now represents a large, clear vesicle, with a lenticular nucleus 

 affixed to the wall, consisting of granules elegantly arranged in 

 a radiate form, which have a small nucleolar corpuscle in the 

 centre. Meissner observed this process in several Ascarides, 

 and thinks that in the end he entirely agrees with Reichert's 

 observations on Strongylus. The only difference between them 

 is that Reichert allows a cell-gemmation to precede the first 

 gemmation of male germ-cells. Reichert did not see the division 

 of the germ-cells, but speaks of endogenous cell-formation of the 

 development-cells of the seminal corpuscles, around the contents 

 of the mother-cell, which, according to Meissner, may occur not 

 only in species of Mermis, but also in true nematode worms. 

 According to Meissner, the seminal elements, during their stay 

 in the testis, usually remain in the last-mentioned stage of deve- 

 lopment (in the form of vesicles or globules of —" in diameter), 

 and in this state they reach the female vagina. From this glo- 

 bular form results the mode of action of the penis of the Nema- 

 toida in copulation, which will hereafter be described. More- 

 over, according to Meissner, the seminal corpuscles are found in 

 tliis state in the vagina, in the uterus, and in the albu- 

 minigene, but rarely in the tuba, from which they are quickly 

 evacuated. 



Thompson describes the formation of the seminal corpuscles 

 from the individual segments of the seminal cells in the following 

 way : In the vas deferens we find an immense number of nucleated, 

 granular cells, of various forms, but equal size (^ — ujoo")> with 

 their contents for the most part uniformly granular, and rarely 

 exhibiting a radiate arrangement. These cells are the freed 

 segments of the seminal cells. Their outer part is indistinct, 

 very finely granular, and only allows an envelope to be detected 

 on the application of water. The more strongly refractive inner 

 part or nucleus, which makes its appearance distinctly on the 



