INTERMEDIARY HOST OF FILARIA IMMITIS LEIDY. 43 



The authors of this paper remark: — "The embryos of Filaria 

 immitis, sucked up with the blood by Anopheles, migrate into the 

 maipighian tubes, where they continue their development, behaving 

 more or less like the other blood filarise already known. The 

 larvae, arrived at the maximum development possible in the body 

 of Anopheles, abandon the maipighian tubes to enter the general 

 cavity of the body, leaving behind the old cuticle, then they pro- 

 gress towards the head, and collect themselves there rapidly (as 

 our transverse sections show very clearly) in the prolongation of 

 the general cavity of the body within the labium, called also 

 inferior labium, (exceptionally also in the palpse). 



"By proper experiments we have demonstrated that when 

 Anopheles bites these larvae come out of the labium, and are thus 

 inoculated in the bitten animal. The mechanism of exit represents 

 one of the most singular and admirable phenomena that one can 



imagine for the diffusion of parasites When the 



mosquito proceeds to penetrate the skin the labium buckles up at 

 first towards the base, forming an obtuse angle. As the stylets 

 gradually penetrate, the angle is advanced towards the middle of 

 the labium, becoming extremely acute, so much so that when 

 complete penetration is effected the labium appears doubled upon 

 itself, forming a narrow kind of loop, and thus forms, through the 

 conformation of the parts which close together, a new canal. . . 

 It is certainly through the bending of the labium stuffed with 

 filarise that is brought about the rupture of the integuments of the 

 labium; along the dorsal groove and through the rupture thus 

 produced come out the filarise to penetrate the body of their 

 definitive host." 



As the European mosquito, the Anopheles maculipennis, does 

 not exist here, it is manifest some other insect must play the role 

 of host in Australia. Early this year I was able to ascertain that 

 the " House Mosquito," Culex Skusii, Giles, was the intermediary 

 host. The embryos go into the maipighian tubes of the mosquito, 

 as stated by Grassi, where they undergo a metamorphosis very 

 similar to that of Filaria noeturna. In twelve days they have 



