MALARIA EXPEDITION TO NIGERIA 25 
make a loop forwards before turning; it coils backwards to a point about one-quarter 
down the length of the worm and receives the two horns of the uterus. In ripe 
specimens the vagina is seen packed with numerous outstretched embryos arranged 
longitudinally. The two uterine horns make many longitudinal coils and twists round 
each other, which may extend up as far as the junction of the oesophagus and intestine 
and backwards to the posterior end of the worm. Near their termination they narrow 
considerably and end in long blunt nodular extremities in the posterior quarter of 
the worm. In the mature worm the contents are first granular in the narrowed 
terminal portion ; the granules increasing in size further on until distinct ova are 
made out. Beyond this they contain embryos coiled up in the vitelline membranes 
which, when the embryos have straightened themselves out, are seen to form the 
embryonic sheaths. In some of our specimens many embryos enveloped in their 
characteristic sheaths have escaped. These and the ova are found to have the 
following measurements :— 
Length of ovum containing coiled up embryo 36 /x 
Breadth „ „ „ „ 23 n 
Length of freshly hatched embryo 76-5 fL 
Breadth ,, ,, 8*2 ^ 
The male is much smaller than the female. It is found in similar positions, 
and in general characters resembles the female, although it is shorter and thinner : 
it is characterised in preserved specimens by the strongly incurved tail, which makes 
two almost complete turns. Its average length is 7-5 mm., its breadth c 1 5 mm. 
Cobb's formula : ~> ™* iC 
- 1*63, 1-63, T-02, 
The head end (plate I, fig. 4) is similar in shape to that of the female. The 
length of the oesophagus is 0*32 mm. There is a distinct cardiac constriction. 
The anal orifice appears to be placed, not exactly terminal, but rather on the ventral 
surface. There are three pairs of pre-anal and one pair of post-anal papillae ; the 
posterior two of the pre-anal series are larger, and are united by low ridges with the 
corresponding papillae of the opposite side. There are two spicules of unequal 
length — not extruded in our specimens. The tail end (plate I, fig. 5) does not taper, 
the extremity somewhat resembles that of the female, except that dorsally it is not so 
abruptly rounded off. 
The embryo. The habitat of the embryo seemed to be essentially the lymph. 
In the process of the preparation of our specimens, it was often observed that in 
those made from the blood of the claws and legs by puncture of a small blood-vessel, 
one only, out of many slides, was occasionally found to contain very few embryos ; 
many contained none at all. Moreover, we never found any embryos in the heart's 
D 
