250 ^ TIMOTHY RICHARDS LEWIS. 



amiued the stomaclis of mosquitoes and of other suctorial insects 

 in a cursory fashion during the last few years, but had never de- 

 tected parasites resembling the FUaria sanguinis. When, how- 

 ever, I learnt of Dr. Hanson's success, I proceeded to make 

 examinations in a systematic manner, and found, to my surprise, 

 that 14 per cent, of the insects, caught at random and then ex- 

 amined, contained such embryos.^ It became, therefore, manifest 

 that filarious blood must be a tolerably common occurrence. 



At first I was not successful in being able to detect any but 

 disintegrative changes in the ingested parasite owing to the 

 circumstance that I had carefully restricted the examination to the 

 contents of the stomach only. This was done in order to 

 diminish the risk of confounding the various stages which the 

 embryo-filarise might undergo with some other parasites which 

 might exist among the tissues of this, as of other insects. The 

 parasites were, in fact, found to be digested. Leuckart^ mentions 

 that a similar result was observed by Fedschenko to follow the 

 ingestion of Dracunculus-embryos in the stomach of the Cyclojjs. 

 The latter is believed to serve as an intermediary host for the 

 development of the guinea worm, the embryos getting into the 

 body of the Cyclops by piercing the cuticle. When, on the other 

 hand, the embryos are swallowed they are digested. 



In the ccurse of the foregoing observations it was observed 

 that all the mosquitoes captured in one of the servants^ houses 

 contained haematozoa of the same character, and it was found 

 that one of the five persons dwelling in this house harboured 

 filarise in the blood. The man had been many years in the place 

 and is not known to have suffered from any special disease. 



The circumstance that such a constant supply of filarious 

 mosquitoes, of tolerably certain history, was available, materially 

 simplified the course of investigation, which, briefly told, was as 

 follows : 



Insects were caught early in the morning in the room in which 

 this person had slept, just as Dr. Mansou had done. Some were 

 placed in bell glasses standing in water, others in test-tubes con- 

 taining a little water at the bottom and covered with a strip of 

 muslin. These were duly labelled and set aside for periodical 

 examination. 



When the insect was examined with recently ingested blood 

 in its stomach, it was found that the hsematozoa, when present, 

 did not differ materially from the aspect presented by them when 

 extracted directly from the blood of its previous host (PI. XII, fig. 

 5), although, not unfrequently, parasites would also be seen which 



' ' Proceedings of the Asiatic Society of Bengal,' March, 1S7S, p. 89. 

 2 Op. cit., Band ii, p. 706. 



