62 THOMAS L. BANCROFT. 



number examined about that time contained no filariae. In the 

 case of Culex nigrithorax, Macquart., C. procax, Skuse, and 

 Anopheles musivus, Skuse, I have been unable to keep them alive 

 more than three days ; a good many experiments were made with 

 Anopheles musivus; this mosquito sucks out a very large number 

 of embryos, and the most of these migrate to the thorax. 



For the scientific names of the mosquitoes I am indebted to 

 Henry Tryon, Esq., Entomologist to the Queensland Government. 

 Thanks are due also to E.S., the filariated subject, without whose 

 assistance this investigation could not have been carried out, and 

 Manson's important discovery might for some time to come have 

 remained unbelieved. 



Explanation of Figures. 



Figs. 1 to 6 — Stages of Filarial Metamorphosis. x about 200 

 diameters. 



Drawings to scale were made of the filaria x 1,000 diameters, 

 afterwards reduced by photography. 



Figs. 7 and 8 — Apparatus for collecting and storing mosquitoes. 



Added June 1st. 



A number of mosquitoes imbibed filariated blood on April 26th 

 and the final stage of the metamorphosis did not occur in them 

 until May 31st, i.e., thirty-five days. The weather was cold. 



It has occurred to me that the young filariae may gain entrance 

 to the human host whilst mosquitoes bearing them are in the act 

 of biting. The entrance of warm blood into the mosquito may 

 excite the young filariae in consequence of which they pierce the 

 oesophagus and pass down the proboscis into the human skin. 

 In this way injury from the human digestive agents would be 

 avoided ; it is not unreasonable to suppose that like water the 

 digestive fluids would soon kill the young filariae, but it is probable 

 that those that may have been set free by rupture of the mosquito's 

 body would immediately pierce the mucous membrane and enter 

 a lymphatic or other vessel. 



