220 



FILARIA IMMITIS 



[CH. 



Distribution. F. immitis is very common in China and 

 Japan where most of the dogs are infected. It is also common 

 in Italy, especially in the marshy districts round Pisa and Milan. 

 It has also been recorded from England, France, Denmark, 

 Germany, Australia, Fiji, the United States and Brazil. 



Fig. 57. A, view of the heart of a dog infested with Filaria immitis 

 Leidy ( X J) ; the right ventricle and base of the pulmonary artery have 

 been opened, a, aorta ; h, pulmonary artery ; c, vena cava ; d, right 

 ventricle ; e, appendix of left auricle ; /, appendix of right auricle. 

 B, a female F. immitis removed from the heart to show its length. 

 Natural size. (After Shipley.) 



Description. The adult is a filiform whitish worm, tapering 

 at both extremities, especially at the tail, and rounded ante- 

 riorly. The mouth is terminal, and surrounded by six, small, 

 indistinct papillae. The anus is near the end of the tail. The 

 male is 12-18 cm. in length by oy-o'g cm. in breadth, 

 and possesses a spirally wound tail, bearing two small lateral 

 ridges supported by papillae. According to Schneider there 

 are 11 papillae, six of which are post-anal. From the anus 



