MTIOLOGY 



1599 



embryo passes into the labium, and when the mosqmito bites, it 

 works its way through Button's membrane on to the skin, its passage 

 being favoured, according to Fiilleborn, by high air-temperatures 

 and moist conditions of the skin. Arrived on the skin, it may work 

 its own way into the body through the skin hke an /Vncylostoma 

 embryo; or it may enter through the aperture of the mosquito-bite 

 when the stilettes have been removed, for before this takes place 

 it is impossible for it to pass through this aperture, which is com- 

 pletely filled by these appendages. 



Its further history and wanderings in the body are quite unknown 

 until the adult condition is reached. The adults (males and 

 females) are generally found lying together, though the females 

 appear to be in preponderant numbers in lymphatic vessels, but 

 they can also be found in the lymphatic glands; while dead and 

 calcified worms have been found not merely in lymphatic glands, 

 but also in the testes, epididymis, spermatic cord, and tunica 

 vaginalis. Here the female produces the thin Microfilarm, which 

 pass through the lymphatic glands and thoracic duct into the blood 

 stream, in which they are found in large numbers at night, retiring 

 in the day-time mostly into the bloodvessels of the lungs. 



When taken into the mosquito's stomach they escape from their 

 enclosing egg-shell, and, entering the thoracic muscles, complete the 

 cycle of development. 



It is interesting to note that in various parts of the tropics natives believe 

 that elephantiasis and other filarial diseases may be transmitted through 

 sexual intercourse. 



The adults lying in the lymphatic vessels may mechanically cause 

 obstruction to the flow of lymph, and thus produce varices, inflam- 

 nation of vessels and glands, and if the varicose vessels rupture, 

 xtravasation of lymph or chyle. 



While this setiological relationship of the worm to the lymphan- 

 itis and lymphatic abscesses, to the varices in lymphatics and 

 ymphatic glands, to haemato-chyluria and chylous extravasations, 

 "s admitted by all observers, there are those who doubt this relation- 

 hip with regard to elephantiasis. These authors base their objec- 

 ions upon the facts that the worm and its larvae may be absent in 

 ell-developed cases, and that the disease can occur in countries 

 n which filariasis is believed not to be present, both of which are 

 uite true, but are capable of explanation. There is an undoubted 

 eneral relationship between the number of cases of filariasis and of 

 ■lephantiasis in a district. Where there is no filariasis, elephantiasis 

 ,is either extremely rare or unknown ; where there is abundant 

 lariasis, there are also many cases of elephantiasis. 

 In investigating this point in a locality care must be taken to 

 xclude immigrant cases of both filariasis and elephantiasis. Thus, 

 _ow failed to find either condition in the inhabitants of the forests 

 of British Guiana and in the Wagandas, natives of Uganda, though 

 immigrant cases were met with. 



