EBVIEW — TROPICAL MEDICINE, ETC. 71 



Low that in a country where filariasis was prevalent patients who were the subject of elephantiasis were rarely Filariasis — 

 affected, or at all events seldom showed eiiiljryos of the parasite in their blood. This, he thought a strong proof continued 



that the parasite was the cause of the disease, something having happened to the subjects of elephantiasis 

 previously, when they wore actively infected with filariae, which set up the elephantiasis and caused the death of 

 the parasite. 



In his reply. Low stated that though all elephantiasis w.as not filarial in origin the vast majority of tropica! 

 cases were due to this cause. He thought the death of the parent worm plus streptococcus might be the real 

 factor. He had traced the development of elejihantiasis in Barl^ados, where there was no malaria, from the initial 

 fever and so-called ague, through recurrent attacks of lymphangitis to the true elephantiasis state. Embryos, 

 however, were not found in the blood of those subject to the lymphangitis attacks, a curious fact which, however, 

 did not vitiate his conclusions. 



Wellman's suggestion, anticipated, however, in some measure by Feldman, has been 

 mentioned. He' records work on OriiifJwdoros moubata, in which tick lie found what he 

 believed to be developmental forms of F. perstans. He thinks that the cycle is probably 

 direct, from man to tick and from tick back to man. His experiments were carefully 

 conducted and his results appear more reliable than those of Feldman,- who claimed that 

 ticks (species not stated) take up F. peisfaus when sucking infected blood, that the worms 

 undergo a certain development in the ticks and pass out with the eggs, being deposited in 

 ripe bananas. These arc ingested and the filaria bore their way into the tissues of the 

 abdominal cavity and assume the adult form. Wellman was unable to confirm these 

 observations and points out certain fallacies in them, one being that microscopic nematodes 

 occur naturally in bananas. 



Several recent papers deal with the development of filarias in mosquitoes. Thus 

 Lebredo^ worked at the metamorphosis of filaria in the body of Culex pipiens. The paper 

 goes minutely into details, and only portions need be quoted. Having traced the embryo 

 from the blood to the stomach and then to the thorax of the mosquito, he finds that the 

 embryo rests in the thorax and goes through the following transformations : — 



(a) Narrowing and invagination of the tail. 



(b) Invagination continues and the embryo grows shorter and wider. 



(c) Widening and shortening continue and the invaginated portion forms a hyaline appendix. 



(il) Period of growth and formation of the three lobes (at caudal cud). He further states : " It happens 

 sometimes, though rarely, that when the filaria reaches its maximum size, and starts on its way to the head, it may 

 mistake the route, and wander towards the caudal extremity. The worm, however, will always keep in the fatty 

 tissue, and close to the chitiuous covering. These stray worms all proceed from the thorax. I have never met 

 with a single embryo undergoing the process of metamorphosis in any other structure than the thoracic muscles." 



The characters which lead one to the conclusion that the filaria has completed its cycle 

 of development in the mosquito are stated to be : — 



1. The arrival in the labium. 



2. Complete development of the three caudal lobes. 



3. Active motility. 



Several other points are emphasised : — 



(I.) When a mosquito falls into the water, if its cuticle be preserved, the filariae it may contain arc unable 

 to escape, and perish by imbibition of water within a period of 24 hours. (lI.) The filaria docs not pass fi-om the 

 living mos<iuito in the act of suction of water or sugar. This rather tends to show that it is not likely to p.ass 

 into bananas. Interesting experiments on the exit of the filaria from the proboscis arc recorded. They lead to 

 the conclusion that the heat in human blood is a factor in determining the exit of the filaria at the moment of 

 the mosquito biting. 



The author also concludes that only a series of accidents could bring the filaria to the 

 human stomach as in the suggested imbibition of water. 



The page on Histological Technique is certain to be found useful, and I transcribe 

 it in toto : — 



For studying the distribution of the filariaj in the body of the mosquito, sections are best used. 



On the other hand, if we wish to follow the cycle of development of the parasite, of its dimensions and 

 structure, we must dissect the infected mosquitoes. 



Technique for the prcjMration of sections — 



1. The live mosquito is placed iu absolute alcohol. In this manner the pouetratiou necessary for fixation and 

 dehydration is obtained. Duration 24 hours. 



1 Wellman, P. C. (July 20th, 1907), "Preliminary Note on Some Bodies Pound in Ticks— Ornithodoros 

 moubata — Ped on Blood containing Embryos of Pilaria." British Medical Journal, p. 142. 



= Feldman (April 15th, 1905), " On Filaria Perstans in the Bukota District." Journal of Tropical Medicine, 

 p. 125, Vol. VIII. 



^ Lebrcdo, M. Q. (May, 1905), " Metamorphosis of Filaria in the Body of the Mosquito CCulcx Pipiens)." 

 Journal of Infectiuus Diseases, Suppl., No. 1, p. 332. 



