8o TROPICAL MEDICINE AND HYGIENE 



very much smaller, than the females, and the posterior 

 extremity is usually much coiled. Most of the Filariidae 

 are viviparous. Development of the larva, where it is 

 known, takes place in an intermediate host an arthro- 

 pod to a certain but limited extent. -Sexual maturity 

 and full growth is only attained when the larva is again 

 introduced into the warm-blooded host. 



Several filariae are found in man ; they inhabit the 

 lymphatics or cellular tissues. In some the embryos 

 find their way into the blood and circulate with that 

 fluid. For diagnostic purposes the larval characters 

 are of greater importance than the adult, as the latter 

 can usually only be found after the death of the host, 

 whilst the embryos are easily found in the blood during 

 life. 



FlLARIA BANCROFTI. 



Filaria bancrofti inhabits the lymphatics or lymphatic 

 glands in various parts of the body, but has more 

 commonly been found in the lymphatics in connection 

 with the pelvis or extremities than elsewhere. The 

 female is 80 to 90 mm. in length, and at its broadest 

 part 0*23 mm. in breadth. The vaginal opening is 0*66 to 

 075 mm. from the head and the anal 0*22 mm. from the 

 tip of the tail. The tail end is pointed. There are no 

 cuticular thickenings or markings on this worm, but 

 there are six pairs of minute papillae on the head (fig. 40). 

 The junction of the oesophagus and midgut is difficult 

 to make o,ut. The male, 44 mm. in length and o'i mm. 

 in breadth, has a blunted tail. Sensory papillae are very 

 minute, but, according to Leiper, the nerves going to 

 them can be seen, and the papillae are numerous anterior 

 to the cloaca (fig. 40). The anterior spicule commences 

 in the body as a pitted, trumpet-shaped, chitinous ex- 

 pansion and may be protruded for a considerable dis- 

 tance. The posterior spicule is broader, flatter, and short. 



These filariae may be found in clumps in the lymphatics, 

 and the embryos passed into the lymph are naturally 



