96 LECTURE VI. 



The Medina or Guinea-worm (Filaria medinensis, Gmel.) is de- 

 veloped in the subcutaneous cellular texture, generally in the lower 

 extremities, especially the feet, sometimes in the scrotum, and also, 

 but veiy rarely, beneath the tunica conjunctiva of the eye. It 

 appears to be endemic in the tropical regions of Asia and Africa. 



The length of this worm varies from six inches to two, eight, or 

 twelve feet ; its thickness is from half to two-thirds of a line ; it is of 

 a whitish colour in general, but sometimes of a dark brown hue. The 

 body is round and sub-equal, a little attenuated towards the anterior 

 extremity. In a recent specimen of small size, we have observed 

 that the orbicular mouth was surrounded by three slightly raised 

 swellings, which were continued a little way along the body and 

 gradually lost ; the body is traversed by two longitudinal lines 

 corresponding to the intervals of the two well-marked fasciculi of 

 longitudinal muscular fibres. The caudal extremity of the male is 

 obtuse, and emits a single spiculum ; in the female it is acute, and 

 suddenly inflected. 



The Filar ia meditiensis, as has just been observed, is occasionally 

 located in the close vicinity of the organ of vision ; but another much 

 smaller species of the same genus of Nematoidea, infests the cavity of 

 the eye-ball itself. 



The Filaria oculi humani was detected by Nordmann in the liquor 

 Morgagni of the capsule of a crystalline lens of a man who had under- 

 gone the opei-ation of extraction for cataract under the hands of the 

 Bai'on von Griife. In this instance the capsule of the lens had been 

 extracted entire, and upon a careful examination half an hour after 

 extraction there were observed in the fluid aboTe mentioned two 

 minute and delicate FilaricB coiled up in the form of ring. One of 

 these worms, when observed microscopically, presented a rupture in 

 the middle of its body, probably occasioned by the extracting needle, 

 from which rupture the intestinal canal was protruding ; the other 

 was entire, and measured three-fourths of a line in length ; it pre- 

 sented a simple mouth without any apparent papillas, such as are 

 observed to characterise the large Filaria Avhich infests the eye of 

 the horse, and through the transparent integument could be seen a 

 straight intestinal canal, surrounded by convolutions of the oviducts, 

 and terminating at an incurved anal extremity. 



The third species oi Filaria enumerated among the Entozoa hominis 

 is the Filaria hro7ichialis ; it is described by Treutler * as occurring in 

 the enlarged bronchial glands of a man : the length of this worm is 

 about an inch ; it is slender, subattenuated anteriorly, and emitting 

 the male spiculum from an incurved obtuse anal extremity. 



* LXXXVI. p. 10. 



