44 
THOMPSON YATES LABORATORIES REPORT 
together ; sometimes there are found several in a bunch in cyst-like dilatations of the 
lymphatic vessels, sometimes they inhabit the larger lymphatic vessels. The female 
is the larger, both in length and thickness. The length varies from 88 to 155 mm., 
the breadth from 0'6 to 0-7 mm. We have been unable to obtain Cobb's formula 
for this worm. The body is plain, tapering towards the rounded head end rather 
abruptly to a neck, which is about one-third the width of the body ; beyond which it is 
enlarged somewhat. The cuticle is finely striated. The mouth is terminal, simple, 4^ in 
width. The tail end tapers and ends bluntly. The anus opens on the ventral 
surface at a distance of 0-13 mm. to 0-28 (according to the size of the specimen) 
from the posterior extremity, on the summit of a projection which resembles a bilobed 
papilla. At the extremity of the tail the cuticle presents a small depression, 
surrounded by two small lips. The vulva is situated at a distance of 1-26 mm. to 
2-56 mm. (according to the size of the specimen) from the anterior end. The worm 
is ovi-viviparous. The ova measure 25 /n to 38 by 1 5 p.. 
The male has a length of about 83 mm., breadth 0*407 mm. The 
body is cylindrical, tapering gradually from the anterior to the posterior end. 
The tail is vine-tendril like, the extreme end being sharply incurvating, making one 
or two spirals. The cuticle is delicately striated transversely. The anterior end is 
rounded, and not marked off by a neck from the rest of the body. The mouth is 
circular, simple, and terminal. The cloaca opens on the ventral surface at O'li mm. 
from the extremity. The tail end presents four pairs of pre-anal and four pairs of 
post-anal papillae, having a wide base. The oesophagus has a thick muscular wall, 
which gives it the appearance of a pharyngeal bulb : it is 0^99 mm. long, and is well 
marked off from the intestine. The genital tube is single. The cloaca gives exit to 
two unequal spicules. 
The embryos measures from 270 to 340 m long by 7 to 1 1 p. wide. 
Manson 1 describes the parasite and its movements thus : — ' In fresh blood, 
F. nocturna is seen to be a minute, transparent, colourless, snake-like organism which, 
without materially changing its position on the slide, wriggles about in a state of 
great activity, constantly agitating and displacing the corpuscles in its neighbourhood. 
At first the movements are so active that the anatomical features of the filaria cannot 
be made out. In the course of a few hours the movement slows down, and then one 
can see that the little worm is shaped like a snake or an eel — that is to say, it is a long, 
slender, cylindrical organism, having one extremity abruptly rounded off, the other for 
about one-fifth of its entire length gradually tapering to a fine point. 
When examined with the low power, it appears to be structureless ; with a high power, 
a certain amount of structure can, on close scrutiny, be made out. In the first place, it 
can be seen that the entire animal is enclosed in an exceedingly delicate, limp, 
structureless sack, in which it moves backwards and forwards. This sack or "sheath" 
1. Manson, Tropical Diseases, London, 1900 ; p. 485. 
