398 THE ANIMAL PARASITES OF MAN 



DISTINCTION BETWEEN Mikrofilaria bancrofti AND Mikroloa ha. 

 Dry Films, Hcematoxylin Staining : 



Mf. bancrofti. Ml. loa. 



(1) In graceful curves (but only if (i) Kinked. 



quickly dried). 



(2) Tip of tail free from nuclei. (2) Nuclei extend to tip. 



(3) Column of nuclei separated by (3) Not so distinctly. 



a space from the cuticle. 



Azur Staining : 



(4) Gi cell small, easily overlooked. (4) Gi cell large, stains deep blue, 



cell protoplasm = twice width 

 of larva, easily seen. 



(5) Excretory cell close to excretory (5) Excretory cell farther from pore, 



pore, 2 per cent, of length. 4 per cent, of length. 



Vital Staining with Neutral Red : 



(6) Internal body or reserve mate- (6) Not shown. 



rial clearly shown. 



Life History. In the stomach of the mosquito the larvae cast 

 their sheath in the thickened blood in one to two hours. In twenty- 

 four hours the majority have reached the thoracic muscles, where 

 development proceeds. They are at first immobile and of a " sausage " 

 form (IIO/A by 13/4), with a short spiky tail. In three to five days the 

 oesophagus is formed, the larva now being 0-5 mm. long. The larva 

 appears to moult at this time. After the gut is formed papillae, three 

 or four in number, appear at the tail end. In two to three weeks 

 the larvae are 1-5 mm. long. They now leave the thorax and reach the 

 labium, but they may be found in various parts of the body, e.g., the 

 legs. They bore through Button's membrane and so arrive on the 

 surface of the skin, which they rapidly enter. Their development in 

 man is unknown, but it may be very long, as children are not infected 

 till 4 to 5, or even lo^years old, but this may be due to unknown 

 causes. , 



Development takes place in numerous mosquitoes. Anophelines : 

 Myzomyia rossii, Pyretophorus costalis, Myzorhynchus sinensis, Myzo- 

 rhynchus barbirostris, Myzorhynchus peditceniatus. 



Culicines : Culex pipiens, Culex fatigans, Cnlex skusei, Culex 

 gelidus, Culex sitiens, Culex albopictus, Stegomyia fasciata, Stegomyia 

 pseudoscutellariSy Stegomyia gracilis, Stegomyia perplexa, Mansonioides 

 unifonnis, Mansonioides*annulipes, Scutomyia albolineata, Tceniorhynchus 

 domesticus. 



Partial development takes place in other species. 



Pathology. Among the conditions which Filaria bancrofti is 



