FILARIA BANCROFT I 



637 



in Fiji does not develop so well in Culex fatigans as it does in 

 Stegomyia pseudoscutellaris Theobald, 1910. 



This latter mosquito feeds only b} day, and in Fiji Bahr has found that the 

 microfilaria occur in the peripheral blood both during the day and during 

 the night, and believes that the periodicity usually observed in the micro- 

 filaria is dependent upon the habits of the insect host. 



Fig. 270. — Scheme of the Structure of a Microfilaria, showing 

 (i) the Excretory Pore; (2) the Cells, which will form the 

 Excretory Apparatus; (3) the Subcuticular Cells; (4) the Genital 

 Cells; (5) Anus. 



(After Fiilleborn.) 



The number of MicrofilaricB in the blood varies from very few 

 up to quite considerable numbers, reaching, according to Manson, 

 up to 500 in a single film, which gives some 40,000,000 to 50,000,000 

 in an average-sized man. This 

 naturally raises the question of, How 

 many adults do these come from ? 

 How long does an adult live ? How 

 long does a Microfilaria live ? What 

 finally happens to the Microfilaria ? 



It would seem probable that a given 

 Filaria can live several years in the 

 human body, and, of course, give 

 rise to many embryos. Further, 

 numbers of Filaria can be met with in one individual. 



Fiilleborn has shown that MicrofilaricB can live in the blood for 

 several months, and observers have thought that they may be 

 destroyed by leucocytes and endothelial cells. It is,^ however, 

 evident that they develop no further in the human body, and 

 require to be taken into the body of a mosquito before further 

 development is possible. 



In the Mosquito.— Khoxm&ing as they do in the peripheral blood 



Fig. 271. — Early Stage of the 

 Development of Filaria 

 bancrofti Cobbold in the 

 Muscles of Culex fatigans. 



(After Looss, from Mense's 

 ' Tropenkrankheiten.') 



