Filaria loa 31 



have been noted ; thus the few cases first recorded from the 

 West Indies include two of children, while in Europe that of 

 Lacompte (No. 33) concerns an infant Congo negress. One 

 missionary in Africa notes that the work of the native children 

 in school is interrupted by the periodical visits of the parasite 

 to the eye. This early infection in the case of natives will insure 

 the attainment of maturity by the parasite and the presence of 

 embryos in the blood of the adult negroes even though the devel- 

 opment of the parasite proceeds very slowly, while the same 

 slowness in development would render it unlikely that embryos 

 could be obtained from the blood of hosts who had been exposed 

 to infection first in middle life. This would serve to explain the 

 absence of embryos from individuals as heavily infected as Rob- 

 ertson's patient who, even ten years after the first infection, had 

 no embryos^ in her blood (cf. the recent account of this case in 

 Habershon, 1904). 



Looss (1905:167) has already called attention to certain dif- 

 ferences in appearance between the illustrations of F. diurna 

 given by difl^erent authors. This indicates either a confusion of 

 what are distinct species, as he suggests, or slight differences 

 in structure due to age of the embryos and accompanying growth 

 or ecdysis. The descriptions of these microfilariae are so gen- 

 eral as to render a precise comparison difficult. In fact Brumpt 

 originally regarded the embryos which he observed in the circu- 

 lating blood as a new species which he denominated F. Bourgii, 

 but later acknowledged their identity with F. diurna. It 

 remains uncertain even yet whether the latter name may not 

 include more than a single species. 



TAXONOMY 



All the earlier observers regarded the eye worm as an erratic 

 Guinea, w^orm. In 1805 Guyot recorded the evidence, already 

 quoted in this paper, which led him to the view that it was dis- 



^ Ziemann (1905:421) emphasizes tlie difficulty nf determining tlie fact, 

 and savs that to demonstrate tlie embryos in tlie blood it is necessary often 

 to try for several days and nights and to take blood from tlie region of the 

 swellings. The distribution of the microfilariae in the body is exceedingly 

 irregular. 



301 



