﻿OBSERVATIONS UPON FILAKIA PHILIPPINENSIS. / 



times as many filariae as it is possible for us to obtain in a similar amount 

 of blood from a needle prick. Thus, in good thick smears under 22- 

 millimeter (3-inch) cover-glasses, we will usually find but one or two, and 

 oftentimes no filariae. In the blood from the stomach of a mosquito which 

 lias recently bitten, the amount of blood usually appears to be less than in 

 these thick cover-slip preparations, but it is nearly always possible to find 

 from 40 to 80 filariae, and it has occurred to us that this fact might have 

 a practical value in examining cases of suspected filariasis in which the 

 parasites are so few in number as readily to be missed. It might be of 

 use in revealing embryos in the blood of cases of elephantiasis, where the 

 filariae, though believed to be present, are seldom found. We have not 

 had an opportunity to put our suggestion into practice except on our 

 last four cases of known filariasis, in all of which the result has been 

 as stated. 



Once, in the stomach of the mosquito, the filariae continue their active 

 motion, which is more uniformly progressive than in the fresh blood, 

 for several hours (the exact length of time we are unable to state) until 

 they discard their sheaths and pierce the stomach wall, entering the body 

 cavity. 



Stages of growth of Filaria philippinensis within Culex fatigans Wied. — 

 It is necessary to state here that the various stages of growth are not 

 passed through in uniform intervals of time but that the jDeriods mentioned 

 below, as well as the measurements given, are thought merely to represent 

 averages. Thus, embryos free from their sheaths may be found in the 

 tissues outside of the stomach, while others ingested at the same time are 

 still struggling in the stomach to free themselves. Likewise, at the eighth 

 day we have, in a heavily infected mosquito, seen some filariae which ap- 

 peared to have undergone fully twice as great a degree of development as 

 others, although we knew that they had all been ingested at one feeding. 

 This preliminary being understood, we may say that in twenty-four 

 hours after ingestion by the mosquito the filaria? have escaped from their 

 sheaths and pierced the stomach wall, being found free in the abdominal 

 cavity. Here they are sluggish in motion, unchanged as to size, but 

 have a more granular appearance. The V spots may often still be 

 distinguished, but the central viscus can not. It is not uncommon to find 

 some of these worms dead and we think that the mortality among them 

 is high at all stages of their development, but more particularly so during 

 the early ones. It is unusual to find more than four or six filariae which 

 undergo the complete cycle of development within the mosquito at one 

 time, while on the other hand only one may remain, and most frequently 

 none are to be observed in the mosquito at the end of ten days or two weeks. 

 Once we encountered fifty-one filaria? in a mosquito's thorax on the 

 eighth day, but we have in no other instance found anything like these 

 numbers after the second. 



