368 DE. P. MANSON OX THE METAMORPHOSIS OF 



Zweifel erlioben, welohe audi die spiiteren Mittheilungen von Lewis nicht beseitigen 

 konnten. Letzterer constatirte zwar ebenfalls, class die Filaria sanguinis hominis in den 

 Magen der Muskitos iibergeht und bier gewisse Veranderungen erleidet ; er fand anch 

 bei denselben jugendlicbe Nematoden, die moglicher Weise einen weiteren Entwickelungs- 

 zustand der aufgenommenen darstellen, aber es ist durchaus nicbt sicber, dass dem in 

 Wirklicbkeit so sei. Von einer anderen Seite konnten die Manson'scben Beobacbtungen 

 nicht bestiitigt werden. Myers wollte dessen Versucbe anf Formosa, wo die Filaria- 

 Krankbeit selbst nicbt autochthon vorkorarat, nacbmachen, kam aber zu dem Resultate. 



dass die Filaria-'Embryoneia. von den Muskitos vollstandig verdant wurden 



Nach alledem miissen wir die Frage iiber die Entwickelung der Filarie noch als ein( 

 schwebende betracbten." These words, I presume, represent the attitude of the 

 scientific and professional mind, on the continent at all events, on the subject of Filaria- 

 metamorphosis. My assertions may be true, but in all particulars they have not beer 

 confirmed, and the evidence I formerly adduced cannot be considered sufficient. 



Impressed by the practical importance and scientific interest of this matter, and being 

 naturally anxious that what I had stated and knew to be true should be accepted, and ' 

 failing decided confirmation from other observers, I thought I could do some service tc 

 my profession and this branch of helminthology if I again went over the ground I bad 

 twice before trodden. With these and other criticisms before me I have done so, anc 

 now endeavour by a short statement of what I found, once for all to settle the matter. 

 This statement I supplemented with a series of illustrative drawings carefully made from 

 fresh preparations and drawn to scale. And, in order that I may quote the testimony 

 of others, I have shown the whole series of my experiments and preparations to Drs. 

 Macleish and M c Dougall, medical men residing in Amoy, and perfectly competent judges 

 on such points. I have their permission to say that they believe my descriptions and 

 drawings to be in the main correct. Further, I have forwarded to friends in England 

 and elsewhere microscopic preparations which, should the frail structures they contain 

 retain the appearances they had when they left my hands, cannot fail to satisfy the most 

 cautious and scientific mind. 



There are three ways by which we may settle the relationship of the mosquito to the 

 Filaria : — 



1st. By tracing the Filaria into this insect, witnessing its metamorphosis therein, and 

 finally its escape at an advanced stage of development. 



2nd. By showing that it is only in those mosquitoes that have fed on filariated blood 

 that the metamorphosis of a nematode occurs — that no such phenomenon can be witnessed' 

 in mosquitoes fed on non-filariated blood. 



3rd. By filariating a man, or a lower animal, by means of Filaria? metamorphosed in 

 passing through the mosquito. 



The first two of these methods I have employed ; the sequel contains a description of 

 my results. The third test of my theory remains to be applied. For myself I have not 

 sufficient hardihood or scientific fervour to attempt it in my own person, but I am con- 

 vinced that a properly planned and conducted experiment would lead to positive results. 

 Both Lewis and Sonsino, besides other observers, confirm me in the statement that the 



