646 



NEMA THELMINTHES 



L, loa is a parasite of the superficial connective tissue- — the 

 conjunctiva, the subcutaneous fat, and the superficial aponeuroses 

 in all parts of the body. It probably only occurs in man, for 

 its alleged existence in sheep and goats in the Cameroons requires 

 further investigation. Its endemic area is on the West Coast of 

 Africa from Sierra Leone to Benguela, being most common in Old 

 Calabar, the Cameroons, and the Ogome River. It is, howeyer, 

 by no means confined to the coast, for it is known to penetrate at 

 least 600 miles into the interior of Africa. 



The cases reported from India are of doubtful validity, and the 

 cases from the West Indies and South America appear to have all 

 been imported from the West Coast of Africa. 



The parasite appears to have never become endemic outside a 

 given area, which means that the animal by which it is spread has 

 a restricted geographical range. 



Fig. 275. — Loa loa Cobbold. Fig. 276. — Loa loa Cobbold. 

 Posterior Extremity of the Posterior Extremity of the 

 Male. Female. 



(After Loess.) 



worm, with a body tapering to each extremity, and measuring 

 25 to 34 millimetres in length and 0-273 to 0-430 millimetre in 

 breadth. The head is like a truncated cone; the neck is but 

 feebly indicated. The tail, more or less incurved, has a rounded 

 tip, from which the anus is distant 74 to 82 There are three 

 pairs of well-marked pre-anal and two pairs of post-anal papillae, 

 with sometimes a little tubercle on each side of the middle line far 

 posteriorly. 



The spicules are two in number and unequal, and are usually 

 stated to differ but little in length. Penel says that the larger is 

 traversed by a fine canal, opening laterally a little distance from the 

 free extremity. 



The cuticle consists of a superficial, thin, translucent layer and 

 a deeper perpendicularly striated layer. Scattered over this 

 cuticle there are rounded thickenings, or bosses, the smaller being 

 9 to II ^ and the larger 14 to 16 ^ in height. The thickness at the 

 posterior extremity is variable, as also is the constriction correspond- 



