30 Henry B. IVard 



such infected regions before the parasite has made its final 

 appearance in the eye. During this time it has undoubtedly 

 made some growth, and at the end of the wandering stage it 

 tends to settle down in deeper tissue. Here the female probably 

 gives birth to the characteristic multitude of embryos which in 

 the circulating blood await the chance of being drawn out into a 

 suitable intermediate host, to follow out again the same life cycle. 

 The adult ultimately becomes encysted and calcified by the activ- 

 ity of the tissue of the host, and Brumpt found four out of five 

 adults in this condition in the case he observed. 



It will be noted that in reality the discovery of F. loa in the 

 eye of a patient in whose blood F. diiirna is present can not be 

 more than an indication of the relationship of the two ; for if 

 the view just advanced is correct the wandering form is not 

 fully mature, and consequently the embryos, if present, must 

 come from F. loa of an earlier infection, and not from the form 

 observed at the same time. This would evidently serve to 

 explain the absence of embryos in those cases, such as Robert- 

 son's already noted, where male and female were taken from the 

 eye and yet blood smears from the host showed no microfilariae 

 present. Among natives in a badly infected region successive 

 infections will be the rule, and wandering semi-adult forms will 

 coexist along with parturient females in deeper tissues and 

 embryos in the circulating blood. In hosts infected during a 

 briefer residence in the infected region such conditions v/ould 

 be little likely to obtain, and embryos would be sought success- 

 fully in the blood only after the cessation of these migrations, 

 when the w^orm is said by many to have disappeared from the 

 body. 



What time interval is necessary for the attainment of the full 

 grown form is not clear. Certainly migrations continue for 

 many years after infection. In the extreme case noted, a worm 

 was removed from the eye thirteen years after leaving infected 

 territory (case 35), and in another, also recorded by Robertson, 

 the parasite is said to have shown itself at irregular intervals 

 for fifteen years before final disappearance into deeper tissues. 

 In the case of natives frequent cases of infection in early life 



300 



