534 
HENRY LESLIE OSBORN 
very conspicuous indeed it suddenly disappears from the series 
of sections, and we may suppose that it is here rudimentary. 
A structure, (vtd in fig. 4), can be seen running from the vitellaria 
toward the region of the oviduct with which the supposed canal 
of Laurer connects. This is filled with cells which are clearly 
yolk cells identifying the duct as the vitelline duct. On the right 
side a larger organ filled with cells is probably the yolk receptacle, 
their connection with the oviduct have not been recognized as 
yet. 
The uterus takes the course indicated in fig. 1, in probably a 
majority of cases, but I have found some varying individuals in 
which it is reversed. Commonly it passes to the ventral surface 
on the right and with more windings than are shown in the draw- 
ing passes to the posterior end of the body. It then crosses to the 
left side and runs forward to the level of the ovary, crosses dor- 
sally to its anterior end and runs forward on the ventral side till 
it reaches the level of the ventral suckers. Its course from this 
point is indicated in the semi-diagrammatic view, fig. 5. 
The uterus in all cases contains some eggs in every part, as can 
be seen in figs. 3, 4 and 5, the older eggs are given a heavier outline 
and are darker. The eggs are not essentially larger in the ascend- 
ing portion of the organ, and excepting for some loss in the dis- 
tinctness of the ovicell in the older eggs there is no evidence of 
development in any cases which have come to my notice (in ten 
series of sections and more than twenty-five whole mounts, and 
very many living worms). The egg measures 0.01 mm. in the 
smaller and 0.02 mm in the greater diameter. There is an oper- 
culum. The older eggs have a very much thicker shell and so 
are much darker. In the whole animal they are black and they 
are responsible for the black spot in the chyle which shows the 
presence of the worm. 
The vitellaria are confined to the central region of the body. 
They lie directly under the surface, externally to the excretor}^ 
cavities and the intestine, their position is shown in fig. 4. There 
are numerous follicles measuring variously some 0.03 mm. across. 
The larger ones are often flattened somewhat. They are com- 
posed as usual of numerous yolk secreting cells. 
