254 rn T. L. BANCROFT. 
On SOME FURTHER OBSERVATIONS on THE LIFE- 
HISTORY or FILARIA IMMITIS, LEIDY.’ 
By THos. L. BANCROFT, M.B., Hdin. 
[Read before the Royal Society of N. 8S. Wales, November 4, 1903.] 
I COMMUNICATED to the Society in June 1901, a paper 
entitled ‘ Preliminary notes on the intermediary host of 
Filaria immitis, Leidy,’’ since then I have had the oppor- 
tunity of following up several points in the life-history of 
this parasite, which remained to be elucidated. 
It was evident that the young or larval filarie, arrived at 
maximum development, as far as their life in the mosquito 
was concerned, passed out, in some way or other, into their 
final hosts, but the exact manner of exit was a disputed 
point. I had myself’ suggested that the worms passed 
down the proboscis into the wound inflicted by the mosquito; 
I did not think it possible for such helpless creatures to 
swim against the blood stream entering the mosquito’s 
stomach by the epipharynx. Afterwards,’ whilst examin- 
ing labia of filariated mosquitoes, mounted in water and 
with a cover glass, it was observed how readily the worms 
escaped from the apex of the proboscis or labium, and it 
was suggested that they naturally thus made their exit. 
Dr. George C. Low considered it probable that the young 
filarize passed out of the labium at its base; Grassi, how- 
ever, could not believe it possible for larval worms, without 
any Special mechanism for boring their way, to pierce the 
1 The expenses of this investigation have been met in part by a grant 
of £58 from the British Medical Association, London July 25th, 1901. 
? Proceedings of the Royal Society of N. S. Wales, Vol. xxx111., p. 62. 
3 Proceedings of the Royal Society of N.S. Wales, Vol. xxxv., p. 44. 
