PART III.] 



The '■'■ Filaria-nursing'" Mosquito. 



623 



By the time that the larval filarise have attained to this degree of development, 

 the mosquito will possibly have already deposited its ova, and its own cycle will have 

 been nearly completed. With the intention of following out the development still fur- 

 ther, I have frequently kept insects until this stage was reached before examination, 

 but all the attempts have proved fruitless, notwithstanding that the mosquito has been 

 seen to go through its ordinary course of depositing its ova on the surface of water, 

 and then perishing itself. Either no filariae were found in its body, or if present they 

 were dead, and careful examination of the water invariably yielded negative results in 

 my hands. It would seem that the larvae had perished. As the quantity of water used 

 was so small, it is hardly possible, had filarise in any stage of growth been present, 

 that they could have so completely escaped observation. Possibly the more or less 

 artificial conditions necessarily associated with the conduct of such experiments may 

 account for these negative results. In the meantime Kcannot, as a result of personal 



Fisj. 02 . . . X 500 diam. 



Embryos of a nematoid helminth from a bird obtained in the stomach of a mosquito. A few blood-corpuscles 



are included in the sketch. 



observation, affirm that a sojourn in the body of the mosquito, and subsequent transfer- 

 ence to water, suffice to bring the Filaria sanguinis -hominis to maturity.* 



A few words may be said regarding other hsematozoic parasites which appear to 

 find their way into the bodies of mosquitoes. In the first place, it may be mentioned 

 that dogs appear to furnish a certain proportion, as I have repeatedly found filarise in 

 these insects in which not the slightest trace of the enveloping cyst, which characterises 

 the human hsematozoon, could be detected. Unfortunately the corpuscles of the dog's 

 blood are so like those of man, as to size and appearance, that it is not possible to 

 distinguish them with certainty, so that the examination of the fluid contents of the 

 mosquito's stomach does not tend to throw any light on the source of the hsematozoa 

 in this instance. It is probable that other animals also contribute towards rendering 

 the diagnosis more difficult. 



* [See on the characters of the true " filaria-nursing " mosquito as got from Amoy. " Observations on Filaria 

 sanguinis-hominis in South Formosa,'" by W. Wykeham Myers, M.B., Surgeon to " David Manson Memorial 

 Hospital," Customs' Report, Shanghai, 1886.] 



