160 
Heligmosomum muris Yokogawa 
end of the ovary consist of flat cells and this part becomes a vacant tube, 
while in the beginning it consisted of large cuboidal cells, showing a more or 
less large, rhombic space between the seminal receptacle and the ovary itself 
(Figs. 32 and 33, Plate XII). When the posterior portion of the ovary forms a 
vacant tube as described above, two pairs of spindle-shaped or triangular cells 
can be seen in its wall at a distance of about 0-04 to 0-06 mm. in front of the 
seminal receptacle (Fig. 36, sr, Plate XII). The region extending between these 
two pairs of cells and the seminal receptacle forms a muscular tube, the oviduct 
(Fig. 33, ov). Both ends of this tube are thickened, forming sphincters. The 
oviduct (Figs. 34 and 35, ov) seems to be an important factor in giving a definite 
form to the fully developed egg-cells as they pass along it singly on their way 
to the seminal receptacle. The length of the oviduct of the adult worm is 
about 0-07-0*09 mm. 
Text-fig. 8. 
Variations in the anterior end of the ovary of adult female. 
The uterus. The uterus develops from the cell-group which is situated 
between the primordium of the seminal receptacle and the ovijector. In the 
beginning of the second parasitic stage it appears as a row of several cuboidal 
cells which increases in length by the division of the cells of its anterior part 
(Figs. 26 and 27, u, Plate XI). The cells in the posterior portion of this row 
gradually increase in width and their centres become vacuolated (Figs. 28 and 
36, u, Plates XI and XII); the increase in the size of these vacuoles produces the 
lumen of the uterus. Toward the end of the second parasitic stage the uterus is 
fully developed and forms a tube except at the posterior part which connects 
with the ovijector. After the completion of the third ecdvsis fully developed 
egg-cells are found in the uterus, and in the posterior end of the uterus the 
wall is thickened to form a sphincter. 
