susceptibility to trypanosoma infection, except in so far as they conduce to opportunity. Thus occupations (boatmen, fishermen, water-carriers) which imply a frequenting of the waterside haunts of the glossina conduce to infection.
Incubation period.—— The incubation period of the glossina-conveyed disease and that resulting from direct artificial inoculation seem to be about the same, from two to three weeks in the case of dogs, horses, and monkeys. As regards man, observations are too few to warrant anything like a definite statement on the point, but in one or two instances circumstances seem to point to a similar incubation period.
Symptoms.—— Without being too definite on the point, and basing the statement on the experience of a limited number of cases, I would suggest that the bite of an infected glossina is followed, in a proportion of cases, by a degree of local irritation of greater or less severity. This subsides in the course of a few days, to be followed, sooner or later, by fever which may last a week or longer, and which may be accompanied by the appearance, in Europeans at all events, of a peculiar type of erythema and a certain amount of serous infiltration of the connective tissue. A form of hypersesthesia, known as " Kerandel's symptom," is usual, though not invariable; if the patient strikes a limb against any hard object, a degree of discomfort amounting to actual pain is experienced, the sensation being slightly delayed. In time the fever subsides more or less completely, to recur at irregular intervals of days or weeks. The fever is sometimes mild, sometimes severe, and occasionally hyperpyrexial (106.6° F.), the evening temperature being always the higher. The fever may last for weeks; the apyretic period may be equally prolonged. On the other hand, the fever may be continuous, or the apyretic period may last for months. Irregularity of degree and duration is a feature of the fever and, also, of the other clinical manifestations of trypanosomiasis. In time the patients become debilitated, anaemic, feeble both intellectually and physically. Headache is very often complained of. The heart's action is generally
