28 Henry B. Ward 



length we are justified in regarding as a female. The specimen 

 reported by Brumpt (1904) measured 60 mm. and yet it was 

 onl}' a part of a female, both head and tail being lacking. The 

 specimens of the female taken from the eye are thus usually if 

 not always only partly grown. ^ How much they fall short of full 

 size can only be determined by the records of specimens, taken 

 from post-mortem examinations, which have settled down in 

 deeper tissues and are found to be producing embryos. 



LIFE HISTORY 



Concerning the life history of Filaria loa only meager facts 

 are at hand, and yet they are so clearly related that one may 

 sketch the main course of development with great probability. 

 Manson (1893) was the first to suggest that the blood-inhabit- 

 ing embryo called F. dhirna was the young form of this species. 

 The agreement in the geographic distribution of the two forms, 

 the certainty that in the infected region the embryonic stage of 

 F. loa must be common, and the absence of any other micro- 

 filaria made the genetic connection of the two almost an estab- 

 lished fact. Yet the negative results of blood examination in 

 several cases which harbored F. loa, especially that of Robert- 

 son (1895) from which both male and female F. loa had been 

 removed, served to cast doubt upon the view. Such doubt was 

 distinctly unjustified since, as I have pointed out, the forms 

 extracted from the eye have been consistently immature and 

 may have been removed before the female has begun the pro- 

 duction of embryos. 



These conditions of probable slow development and of imma- 

 turit}' when in the eye agree well with known facts from related 

 species of Filaria in other animals. Thus F. equina, a common 

 parasite of the horse and ass, which occurs at times in the eye 

 of the host, is found there in the semi-adult form Avhich is also an 

 active migrant. F. labiato-papillosa of deer and cattle appears, 



'If the record of Guyoii (1864) that his specimen was 15 cm. long does 

 not rest on an error in transcribing or printing, it represents a mucli larger 

 and lience more nearly full grown female than any other yet recorded. 

 Ludwig has already shown that this case in all probability concerns /^//rtrzVr 

 loa (cf. Ludwig und Saemisch, 1895:737). 



29S ■ 



