METAMORPHOSIS OF FILARIA BANCROFTI, COBB. 59 



remove the piece of banana and replace by fresh every three or 

 four days. Should the air in the cell become foul from the 

 decomposition of banana, or from the odour of mould fungi or 

 the water at times contaminated by banana juice, it is advisable 

 to liberate the mosquitoes under a mosquito net curtain and 

 transfer them to a clean cell. It is also well to place a plug of 

 cotton wool in the hole in leno and over this the watch-glass, 

 concave side down. The cells are placed in a room in the house 

 where the light is subdued, or shaded by brown paper from too 

 strong a light. Half a dozen mosquitoes is a sufficient number 

 to put into one glass cell of the capacity of one hundred ounces 

 of water. 



When mosquitoes are required for examination, they are liber- 

 ated under the curtains, captured and killed in the entomologist's 

 cyanide bottle, or by means of chloroform etc. Two pairs of 

 ciliary forceps are useful with which to pull off the wings, legs 

 and head ; afterwards the body is divided by dissecting needles 

 into thorax and abdomen, and each portion examined separately, 

 teased out in water, or better in Muller's fluid with or without a 

 cover-glass under a magnification of fifty diameters. 



The following is a short account of the life-cycle of Filaria 

 Bancrofti: — Commencing with the mature parasites in the human 

 subject; these are three or four inches in length by - 9 V' in breadth, 

 they live in the lymphatic vessels ; they produce the embryo 

 filarise, which are / -" x 3-5V0 "\ these latter live in the blood vessels, 

 swimming about when the host is sleeping and resting themselves 

 when he is awake. 



Mosquitoes when biting a filariated subject during the night 

 withdraw together with blood some of the embryo filarise. Soon 

 after the embryos reach the mosquito's stomach they pierce the 

 stomach wall and find their way to some muscular mass, particu- 

 larly the thoracic muscles, in which they imbed themselves (Fig. 3); 

 there nourished by the mosquito's plasma they grow at a pro- 

 digious rate, becoming longer and thicker and assume by the fifth 

 day the appearance represented in Fig. 4, in which a distinct line, 



