412 THE ANIMAL PARASITES OF MAN 



still in the vulva, the larva measures 217 p to 274 /JL (average 246 /JL) in 

 fresh, 146 to 226 p (average 192 //,) stained. 



Site of Worms. In various localities; under the muscular aponeu- 

 roses on extensor surfaces of arms and legs, ringers, trunk, eyelid, 

 conjunctiva, fraenum linguae, penis, pericardium, anterior chamber of 

 eye, and, according to some authorities, in lymphatic vessels, e.g., 

 those of spermatic cord. As many as thirty adults may be found. 

 The worms appear to be frequently immature, and it has been stated 

 that worms in superficial parts are immature, those situated deeply 

 are mature, but the data are few. 



The first accounts of Loa loa long since forgotten were reported by 

 Pigafetta, and are contained in a book of travels on the Congo printed in 1598. 

 In an accompanying illustration is depicted, not only the ancient method of 

 extraction of the Medina worm, but also the operative removal of the filaria from 

 the conjunctiva. Subsequently the presence of the worm in negroes was confirmed 

 by Bajon in Guiana (1768) and by Mongin in Mariborou (San Domingo), likewise in 

 a negro (1770). At about this time a French ship's doctor, Guyot, was cruising on 

 the West Coast of Africa; he observed the parasite termed "loa" by the natives, 

 and learned that it was frequent in the negroes of the Congo district. Since that 

 time numerous observations have been reported. It was formerly common in South 

 America, where the parasite was imported by slaves, but it disappeared when the 

 traffic ceased ; it was particularly prevalent in the Congo, where it occurs not only 

 in natives, but also in Europeans. During recent times it has repeatedly been 

 observed in Europe in negroes as well as in white men who have lived on the West 

 Coast of Africa. 



Nematodes of different size have been repeatedly observed in the 

 eye of man, in the anterior chamber, lens and vitreous. For example, 

 Mercier, in 1771 and 1774, removed a filaria out of the anterior 

 chamber of two negroes in St. Domingo. One was 36 mm. long. 

 Barkan, in 1876, in San Francisco, removed one from the eye of an 

 Australian. Again, Cappez and Lacompte, in Brussels, in 1894, 

 observed for some weeks immature Nematodes in the eye of a negro 

 girl, aged 2\ years, and then removed them. What these Nematodes 

 actually were in these cases it is impossible to say. 



Structure of Laruce. In dried films the larva varies in size from 

 140-5 //, to 166-5 P, average, 152-5/4; while another set of measure- 

 ments gave the values 131/4 to 150/4, average, 143-6. In films fixed 

 with hot alcohol the dimensions were 208 //< to 254 //,, average, 231 //,. 



The nerve ring 21-4 to 21-8 per cent. Excretory pore 30-4 to 31-8 

 per cent. Excretory eel 34-8 to 37-3 per cent. Gi cell 68*2 to 68-5 

 per cent. Anal pore 8r6 to 82-4 per cent of total length. For other 

 details cf. Filaria bancrofti. 



Larva in Blood. These from their diurnal periodicity are known 

 as Mikrofilaria diurna. The evidence that these larvae are the young 

 of the adult worm Loa loa is : (i) They are identical in structure with 



