Fig. 299.—Mf. perstans in thick film, dried and stained with hæmatoxylin; 4, unshrunken; 5, shrunken. × 1,000. (After Fülleborn.)
The adult male measures 45 mm. in length by 60 µ to 80 µ in breadth. The diameter of the head is 0·04 mm. The tail is much curved. There are four pairs of pre-anal papillæ and two pairs of post-anal papillæ. Spicules very unequal in size. Cloaca 121 µ from the tail end. At the tail end two triangular cuticular appendages.
The adult worms inhabit the connective tissue at the base of the mesentery, especially in the region of the pancreas, abdominal aorta and suprarenals. To find them the mesentery should be removed, placed in a 2 per cent. solution of formalin, and then carefully examined at leisure.
Mikrofilaria perstans.—160 µ to 210 µ by 5 µ to 6 µ broad. Has no sheath. Cuticle transversely striated. Tail rounded off, not pointed. Nerve ring at 34 µ. Excretory pore 49 µ, genital pore 125 µ from head. Smaller larvæ 90 µ to 110 µ by 4 µ broad. A “fang” is also described on the head.
| Mf. perstans. | Mf. demarquayi. |
| (1) Tail stumpy. | (1) Tail pointed. |
| (2) Column of nuclei extends to tip of tail. | (2) Does not extend to tip. |
Periodicity.—None.
Life-history.—Unknown.
Geographical Distribution.—Very common in many parts of Africa: Sierra Leone, Dahomey, Northern Nigeria, Southern Nigeria, Cameroons, Ivory Coast, Gold Coast, Old Calabar, Congo, Uganda. Absent from Zululand, Basutoland. On the East Coast of Africa it is not found in the towns of Zanzibar and Mombasa, neither is it found in the country of the Masi, nor amongst the Kavirondo, who dwell along the north-east shores of Lake Victoria.