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XII] frequently,. This species is widely distributed in Africa, from Uganda and Somaliland in the east, and Congo and Angola in the west, to Namaqualand and the Transvaal in the south. In habit Ornithodoros moubata resembles the common bed-bug. It lives in the huts of the natives, hiding during the day in cracks in the walls and floors, or in the thatched roofs, and moving about actively during the night in search of nourishment. It attacks both man and beast. It feeds slowly, and would be unable to get much blood from any but a sleeping person. Dutton and Todd observed that a big female might remain, firmly fixed, feeding on a monkey for two or three hours before it finally dropped off, distended to the size of a cherry. O. moubata deposits its eggs in batches of fifty, seventy, or a hundred. Dissection has shown that only a few eggs mature at a time. The fertility of the female is favoured by liberal feeding. The females lay batches of eggs after each feed, but do not continue to moult. The eggs hatch in about twenty days. In the case of this tick, Dutton and Todd have observed that the larval stage is practically omitted. About seven days after oviposition the hexapod larva can be seen to be forming within the translucent egg-shell. About the thirteenth day the egg-shell splits, and about the same time the larval skin splits also, and the eight-legged nymph throws off simultaneously both the egg-shell and its larval skin. There are several nymphal stages; the exact number has not been clearly ascertained. The largest nymphs may equal adults in size, and show a punctiform mark where the sexual orifice is situated in the adult.

An interesting feature, and one perhaps having a bearing on the etiology of tick-transmitted diseases, pointing as it does to a channel by which the egg.s may receive a germ ingested by the parent, concerns certain cells in the stomach wall. The tick, while feeding, from time to time expels per an uni a whitish material. This excretion is derived partly from the Malpighian tubes, and partly from the cells alluded to. In the stomach wall, nourished by the imbibed blood, these cells elongate towards the cavity of the ventricle; the other end, smaller and becoming clavate, splits and emits the elaborated nutriment into the general body cavity, where it mixes with the blood of the tick. The cell then, becoming globular, drops into the lumen of the stomach, constituting part of the white excretion expelled per anum. One can readily understand how, by the former route, a parasite could reach the tissues of the tick, including the ovaries. Balfour has infected chickens with S. gallinarum by feeding them on eggs of infected Argas miniatus (persicus). O. moubata is especially common along the routes of travel. The rest-houses are always the most infested. The ticks are frequently carried long distances in mats or bedding, or in porters' loads which have been piled for safety in the rest-huts at night. The natives of some places, and also the Boers, protect