50 THOMAS L. BANCROFT. 



to be a good food for them. It was ascertained that unimpregnated 

 mosquitoes lived the longest ; those that had been impregnated 

 lived two or three weeks, whilst the males rarely lived a fortnight. 

 In my former investigation into filarial metamorphosis, it never 

 occurred to me to feed my filariated mosquitoes whilst in confine- 

 ment, accepting the common belief of their only feeding once and 

 dying within a week. Manson, Lewis and Myers, who had worked 

 at the subject, never fed the mosquitoes, and it never dawned 

 upon me that my mosquitoes were dying from starvation. 



Having discovered that mosquitoes could be kept alive long 

 periods in confinement if fed on banana, I was anxious to ascertain 

 what would become of the filarise, which were to be seen in 

 mosquitoes that lived seven days; would they go on developing if 

 the mosquitoes lived longer 1 



Unfortunately E. S., the filariated subject, a girl of sixteen, 

 from whom I had obtained filarial had left the district, having 

 secured a situation as domestic servant ; she was the only person 

 affected with filariasis I knew of. 



Dr. Manson's encouragement and a grant of £7 from the Queens- 

 land Branch of the British Medical Association to defray the cost 

 of E. S. returning and living with her parents for three months 

 and submitting to be bitten by mosquitoes, induced me to enter 

 upon a fresh investigation on February 1st, 1899. It was found 

 that the actively moving filarial were to be seen, but not before 

 the sixteenth or seventeenth day, sometimes in cold weather not 

 until twenty days, and that no further development occurred in 

 them even after a sojourn of sixty days in the mosquito's thorax. 



The final stage of the metamorphosis, i.e., the preliminary 

 alternation of generations, is attained in sixteen or seventeen days; 

 (Fig. 6) the young filarise are then iV' in length by T £o" in breadth, 

 some only iV' x Tiho"', there is no apparent difference except in 

 size ; there is a well marked intestine with oesophageal bulb, also 

 some differentiation of the body protoplasm into reproductive 

 organs (ovary and testicle) but I have not been able to make out 

 any sexual difference. 



