844 SUMMARY OF CURRENT RESEARCHES RELATING TO 



properly so called, is finely granular ; the efferent portion is distin- 

 guished by the large size of the investing epithelial cells. In addi- 

 tion to the papillae, which may be considered as appendages of the 

 genital apparatus, there is a simple straight spicule, which is elon- 

 gated, and unlike in character to any of those figured by Galeb. 

 Speaking generally, we find that the male of 0. curvula presents great 

 afiinities to the male 0. vermicularis. 



Female Organs of Ascaiis megalocephala.* — E. van Beneden, 

 after a statement of the views and descriptions of earlier authors, gives 

 an account of what he observed in a sj)ecimen of moderate size. The 

 vagina, wliich is about 7 mm. long, passes upwards and forwards, and 

 then turns backwards. Quite close to the vulva it enlarges a little ; 

 then there follows the part common to the two uteri ; this is 6 mm. 

 long, and has the form of a truncated cone ; it is continued without 

 any line of demarcation into the uteri ; these are set parallel to one 

 another, and are found under the digestive tube, near the hinder end 

 of the body. ^Vhere they enlarge they form a convexity directed 

 backwards ; they then pass forwards and become continuous with the 

 oviducts ; along the whole of their course we note a slight but gradual 

 diminution in the diameter of the lumen. The oviducts are nodose 

 and transparent ; the nodal points are irregularly distributed ; in the 

 course of the duct there are two or three convolutions, and the length 

 of each is about 9 cm. The ovidiict may be distinguished from the 

 lower part of the ovary by the following method : if a living female 

 is opened in Kroneckcr's artificial serum, and the oviduct be cut 

 through transversely at two neighbouring points, so as to isolate a 

 piece of about 1 cm. in length, there is no contraction of the piece. 

 If, now, a piece of the oviduct be similarly treated, the walls of the 

 tube will contract, the segment will diminish in length, and the con- 

 tained ova will be expelled. 



The author treats in detail of the structure of the various parts of 

 the female generative apparatus. In the ovary the tunic appears to 

 be structureless, and the epithelial layer is formed by longitudinal 

 nucleated fibres, the characters of which differ remarkably in the dif- 

 ferent regions of the organ. The oviduct is somewhat difiicult to 

 characterize, from a histological point of view, as the epithelium of 

 the lower is very different from that of the superior portion of the 

 tube ; and, while the lower portion has an external muscular tunic, 

 there is no such tunic in the upper portion of the oviduct. Nor, 

 again, is the line of demarcation between the epithelial cells of the 

 upper and lower portions a transverse line ; as a matter of fact, we 

 might make a number of sections in which we should find the two 

 sets of cells in different parts of them. The oviduct is best looked 

 upon as being the bond of union between the two chief parts of the 

 generative apparatus — the ovary on the one hand, and the uterus on 

 the other. The author describes the methods by which the cell-layers 

 of the duct can be studied. 



The uterus and the oviduct are best distinguished by the differences 



* Arch, de Biol., iv. (1883) pp. 95-142 (1 pi.). 



