FILARIA IMMITIS 285 



2. Filaria immitis, Leidy, 1856. 



The body is very thin and filiform ; the posterior extremity 

 is pointed, and the anterior one rounded off ; the mouth is 

 terminal, and behind it there are six small papillae ; the anus opens 

 near the posterior extremity ; the male measures 12 18 cm. in 

 length, 0*7 O'Q mm. in breadth ; the tail is slender and twisted 

 like -a cork-screw ; it has a fold of skin at either side and four 

 pairs of large pre-anal, and some smaller post-anal papillae, the 

 surface of which exhibit a smooth appearance. The female 

 measures 25 30 cm. in length and ro 1-3 mm. in breadth ; 

 the vulva is about 7 mm. distant from the anterior extremity ; 

 viviparous ; the larvae measure 0^285 0*295 mm. in length, and 

 0-005 mm. in breadth ;. the posterior extremity terminates in a 

 very thin point. 



Filaria immitis lives chiefly in the right cavities of the heart, also in the 

 venous system of dogs, but appears also to occur in the wolf (Japan) and 

 in the fox ; in Europe it is most frequent in Italy ; it is very frequent in 

 China and Japan, where, according to Janson, about 50 per cent, of the 

 dogs are infected. It has also been observed in N. and S. America. 



According to Bowlby, this species occurs also in man. At the 

 post mortem of an Arab, who had suffered from 'haematuria, this 

 author found numerous filariae in the portal vein, and the eggs 

 of Nematodes in the thickened wall of the bladder, in the kidneys, 

 ureters, and in the lung. Similar eggs are also said to have been 

 found in a rectal tumour in a youth, aged 17. The filariae found 

 were identified as Filaria immitis, 



[The eggs of Nematodes found by Bowlby in the thickened wall 

 of the bladder, in the kidneys, ureters and in the lung of an 

 Arab suffering from haematuria, were undoubtedly those of 

 Schistosoma hcematobium. Probably the worms he found in the 

 portal vein of the same patient were female specimens of Schistosoma 

 and not specimens of Filaria immitis. L. W. S.] 



Large numbers of Nematodes of a considerable length were found in the 

 veins of a Russian whose body was dissected in Dorpat in 1885. Having 

 myself seen and prepared the well-preserved worms I could not fail to 

 observe their filarial nature, but I am not in a position to give more 

 details as I was unable to examine them more minutely. 



The life history of Filaria immitis has been elucidated by 

 Grassi and Noe. It was, however, already known that the larvae 

 appear in the blood of infected dogs, especially during night time. 



The larvae of Filaria immitis, like the malaria parasites, are taken 



