OF FILARIA SANGUINIS HOMINIS. 



311 



of the developed embryo constitute the perfected boring-appa- 

 ratus of the worm, or if it is the boring- apparatus at all ; but 

 comparing this with what is found in other species of the same 

 genus, I think it very probable that it either is or will become the 

 piercing-apparatus. Some time ago I operated on an Australian 

 horse for this worm, and had the satisfaction of finding the para- 

 site not very much injured after removal : it was an unimpreg- 

 nated female possessing all the typical structures of the Filarice. 

 Its head was armed with a five- or six-toothed saw, the teeth ar- 

 ranged, like those in some kinds of old-fashioned trephines, in a 

 circle round the mouth. I removed a worm from the same eye of 

 the same horse about three or four weeks previously ; the cornea 

 had healed, and the cloudiness cleared up before the second worm 

 appeared. I infer from this, from the very perfect boring-appa- 

 ratus, and from the female being unimpregnated, that the eye is 

 not the resting- or breeding-place of the Filaria found in it, but 

 that it is sometimes accidentally entered by the worm on its travels 

 in search of the suitable spot. From the fact that one worm suc- 

 ceeded the other I infer that the sexes are brought together in 

 this way (as in the.case of J5^^7ar^« sanguinolenta of the dog): when 

 a wandering worm comes across the tract of another, it follows it 

 up ; thus several may be found together at the end of the burrow. 



Probably, then, these papillae are the boring-apparatus to be 

 used in penetrating the tissues of man and escaping from the 

 mosquito. At this (presumably the final) stage of the Filaria's 

 existence in the mosquito it becomes endowed with marvellous 

 power and activity. It rushes about the field, forcing obstacles 

 aside, moving indiff'erently at either end, and appears quite at 

 home, and in no way inconvenienced by the water in which it has 

 just been immersed. This formidable-looking animal is undoubt- 

 edly the Filaria sanguinis hominis equipped for independent life 

 and ready to quit its nurse the mosquito. 



Future history of the Filaria. — There can be little doubt as to 

 the subsequent history of the Filaria, or that, escaping into the 

 water in which the mosquito died, it is through the medium of 

 this fluid brought into contact with the tissues of man, and that, 

 either piercing the integuments or, what is more probable, being 

 swallowed, it works its way through the alimentary canal to its 

 final resting place. Arrived there, its development is perfected, 

 fecundation is effected, and finally the embryo Filarice we meet 

 with in the blood are discharged in successive swarms and in 

 countless numbers. In this way the genetic cycle is completed. 



LINN. JOUKN. — ZOOLOGY, VOL. XIV. 23 



