Outside is the tough sheath surrounding the worm, next to it lies a 
narrow cuticular layer; beneath this is the circular muscular coat and then 
the longitudinal; the latter is the thicker. It is interesting to note that 
these layers are thicker over the dorsal and ventral than the lateral regions. 
No special coelomic cavity lined by a special epithelium seems to exist 
although there is a large open space where the alimentary tract and the four 
coils of the ovary lie. 
The intestinal canal may be distinguished by its flattened shape and by 
the cubical granular epithelium evenly laid out. The uterine tube, on the 
other hand, presents a peculiar uneven epithelium lining the interior. 
This is due to the cells projecting inwards with their large nuclei (seen best 
under the one-twelfth oil immersion). These cells are never many, and 
in section usually between 6 and 8 are seen. External to this epithelium is 
the smooth muscle layer which is evenly distributed. Within the lateral 
i longitudinal muscular layer two small peculiar structures looking like nerve 
cords are sometimes seen cut transversely. 
There is no regular water-vascular system. 
A section of the worm at the tapering portion close to the head reveals 
the oesophagus and single uterine tube, slightly thicker here than elsewhere, 
lying side by side, whilst the other structures diminish in size correspond¬ 
ingly. Towards the tail end where the ova are formed, the ovarian tubes 
are more or less solid in character due to the rapid proliferation of the cells of 
the germinal epithelium. 
Ova and Embryos. 
The ova and embryos are not unlike those of many other species of 
Filaria in their appearance. 
In all the young embryos of fertilised ova, a thin capsule completely 
encircling the contents is present. This capsule is oval and possesses some¬ 
times a pointed spicule at one extremity, more often one at both extiemities 
(? micropyle). What the functions of these spicules are it is hard to under¬ 
stand, for when the embryos are fully developed they break through their 
capsules and pass out through the genital opening into the interior of the 
aortic tumour and live amongst the loose granular debris. Their eventual 
destination has not yet been traced. 
The free embryos are found scattered sometimes in very large numbers, 
sometimes in scanty numbers inside the aortic tumour. 
When living, they are extremely active and wriggle out of the genital 
opening after the most peculiar contortions. Once outside, they struggle 
hard in the surrounding media, now coiled up, now straightened, and ever 
restless. No special parts or organs can be detected. \\ hen fresh, the whole 
embryo appears as a refractile granular mass of living substances. Under 
the oil immersion no oesophagus or any definite structure can be seen 
beyond refractile granules of various size, which are not blackened by osmic 
acid and hence are not fat globules. 
In a stained preparation obtained from some of the contents of aortic 
tumour in which these embryos are present, the various structures may be 
more closely observed. 
The length of an embryo is 292 to 325 u. (.29 to 32 mm.) and breadth 
is 3.5 to 4 u. 
