The etiology, prophylaxis, and treat ment of malaria studied_ from two points of view. First, the circumstances bear ing on the introduction of the parasite into man; second, the circumstances af fecting the development of the clinical manifestations of malarial infection. Under the first bead, the knowledge that certain species of mosquito are the necessary media for malarial infection has enabled us completely and satis factorily to explain many facts which hitherto eluded us—such, for instance, as the long-recognized association of malaria with liigh atmospheric tempera ture and paludal conditions. The danger of being out of doors at night in malarial countries is explained by the habits of mosquitoes, whieli are mainly nocturnal. The value of the mosquito net and similar contrivances, of smoke, and of lire as protections from malaria are explained by the circumstances that these things keep the blood-sucking in sect at a distance. The etiology of malaria, therefore, resolves itself ill a great measure into the study of the natural history of eerlain species of mosquito. Especially the gP1111.4 W/Ph - I. r II I he 1.imed to ser‘t. for 1, the parosite.
,• .1 2 11,1, in the life of a mos ], a- 1, How,: The t•gg deposited ..• %tat,' r, at, on the surface or at ta, led to egetat ion at t ,Y1 t p% 01. III 01110111. tWO days .r.. It I.IIN .1 I, 11:11e)1Cd Mit and at • • 1, 111 1, t 0 11'01 greedily • , HIM Crt.11., su-pended in the .1, r It grow- rapidly and finally as , • t 1.111.a fOrIII. from which the ff, ,t in-c, t presently emerges. The ,i.r.tion of aquatic life Naries with dif iti cut -pecie,. and is affected by the mperature. of the water. In C01(1 .1 t deVelOpIllellt entirely sus 1,1. Thi: hibernation of the larva 1-• , e of the ways by which the cold i- bridged across and the species arriva cl' fl'0111 to summer.
c remains quiet during the (lay, fteding at night. The male is in most in,tances purely phytopliagons. The female Aim/dales even in confinement %%ill aceept a meal of blood every two or three day,. About twenty days after birth -lie depo-its some one hundred and fifty or two hundred eggs, an operation r(peated every few days so long as con ditions are favorable. The entire cycle from (.1.= to egg occupies about fifty day-. It is calculated that a single female will give rise in four generations to a progeny of two hundred million. In confinement the mosquito has been kept alive for two months. "Alan is the greJt. source from which the mosquito .1.,t aim the parasite. Young subjects are e•ially suseeptible, individual sus . ptilility being innate or acquired.
few individuals are absolutely im le me to the disease. l'atrick Practitioner. 1\larch, 1901).
(- tilt ivation of the testivo-autninnal ma 1..rasito in the mosquito ,1, grutdrimaetagta) during the past a inter and summer. In the neighbor '.ot I the League Island Navy Yard, Phil,' hlphia, on June 19, 1900, ‘the folind both the larvm of the 1/mplit 4.1/4 qua drini aettlata and the iimph
rior pitn(lipinnis near a hou,e where ca,e of malaria developed. From June 10, 1900, to November 11, 1900, he collected farm of the Atropiwics and raised 200 adult mosquitoes. Ile also visited many infected localities, and always found that where there is ma laria there are mosquitoes. The reverse, however, does not hold, for where there are mosquitoes there are not always cases of malaria. He found some larvm of Anophcles in the Pocono :Mountains of Pennsylvania. A number of observa tions were conducted to see whether the Anonlicics collected around l'hiladelphia were susceptible to the infection from the malarial parasite. In only one ont of ten observations did he find zygotes in the middle intestine of one mosquito. Woblert (Jour. Amer. Med. Assoc., March 2, 1901).
The mountains of Honduras, four thousand feet above the sea-level, are above the mosquito-belt and above the fever-belt, and yet malarial fever, both of the quotidian and tertian types, is of common occurrence. It is propagated, at least in part, by fleas. J. IL Egbert (Medical Record, Aug. 17, 1901).
Experiments were made in a, large gauze tent which had been erected within a disused photographic establish ment, the one end of the tent ending against large windows, into which the sunlight poured on bright days. Large stone basins were placed on the floor for the Altophetes to breed in, the stock being renewed front time to time.
It was noticed at tlte beginning that when one entered the tent in dark-gray clothes the imagos frequently flew up and settled on the dark cloth, but that they never did this when the person en tering the tent Ivas clothed in white flannels. To test the influence of color, a number of pasteboard boxes were taken which measured 20 centimetres by 16 centimetres, and had a depth of 10 centimetres. The boxes were lined with cloth, having a slightly roughened sur face. to which the insects conic] com fortably cling. All of the fabrics had a dull surface. and each box was lined with a. cloth of different color. The boxes were placed in rows upon the floor and upon each other in tiers, the order being changed each day after the observations had been made. The in terior of the boxes were moderately il luminated by light reflected from the surface of the white tent. On 17 days during. a month, beginning with the middle of June, the number of flies which had accumulated in the boxes were counted. Counts were actually made on 17 sunny ford cloudy days, and with the following result:— Dark blue was most attractive, the other colors being less and less attrac tive in the order of numbers given. A marked fall in the number of insects resting in the boxes begins with the "blue" box; the color in this case was a rich, full blue. Pale green, light blue, ochre, orange, and yellow, especially the last two colors, seemed to repel the in sects.