dark-ground illumination, has observed the extrusion of minute refractile granules which, after a brief interval, exhibit active rotary movements and which may constitute a stage in the evolution of the parasite. T. pertenue has been found in the spleen, lymphatic glands, and bone marrow, and, doubtless, it occurs in the blood. It is inoculable into monkeys and rabbits; in the former, especially in the orangoutang, it gives rise to lesions similar to those in man.
Cultivation of T. pertenue has been successfully performed by Noguchi in ascitic fluid containing a piece of fresh animal tissue such as the kidney, the whole being covered with a layer of sterile paraffin. This rather complicated technique has been simplified by the later work of Hata, who substituted horse-serum in which the inoculation is made through the upper solidified layer-. The organisms develop anærobically in the lower fluid layers. To succeed in the cultivation of the pathogenic spirochsetes strict anærobiosis is necessary.
Symptoms. The initial fever.— In yaws there is an incubation stage of very variable duration two weeks to six months*[1]— the appearance of the characteristic eruptions being preceded by a certain amount of constitutional disturbance. The intensity of the general symptoms varies within wide limits. Sometimes they are hardly perceptible, and are not complained of; usually there is well-marked malaise with rheumatic pains. Occasionally there is severe constitutional disturbance, lasting for about a week, with rigor, smart fever— 100° to 103° F.— persistent headache, pains— worse at night— in the long bones, joints, and loins, and sometimes gastric disturbance and diarrhœa. During the decline of these constitutional symptoms the eruption appears.
Stage of furfuraceous desquamation.— The skin becomes harsh and dry, loses its natural gloss, and here and there patches of light-coloured, very fine furfuraceous desquamation, best appreciated with the aid of a lens, are formed. These patches are mostly
- ↑ * Paulet, who inoculated 14 healthy persons with yaws, found the first lesion in from twelve to twenty days; Charlouis, in 28 inoculations, observed a papule at the site of inoculation after fourteen days. Naturally acquired yaws is reputed to have a longer incubation period than the inoculated disease.
