276 The Philippine Journal of Science 192s 



pili muscles seem as usual, and there are no vascular lesions 

 deep in the corium. About the cellular accumulation in the 

 corium there is a moderate proliferation of fibroblasts. 



SPONTANEOUS HEALING 



Nearly all the nodular cutaneous lesions of yaws in the course 

 of time undergo spontaneous healing. After they have become 

 well developed the process is a tedious one and may extend over 

 a period of months or years, those on the palms of the hands and 

 soles of the feet being especially chronic. Most of the macules 

 and papules of the secondary eruption regress before they reach 

 the frambcesiform stage. After the framboesiform appearance 

 is attained, regressive changes become manifest, such as drying 

 of the surface and the formation of a thick keratin coat beneath 

 which papillary projections covered by cornifying epithelium 

 become more conspicuous and pigmentation of the part is in- 

 creased. 



Such a stage of arrested development and regression was rep- 

 resented in the lesions removed from case 5. The process of 

 healing consists in the gradual disappearance of acute exudate 

 (and undoubtedly of most treponemata) from the margins of 

 the yaw. The epidermis becomes again compact and reassumes 

 the differentiation of its cells, so that there are hyperkeratosis 

 and increased pigmentation corresponding to the degree of epi- 

 dermal hyperplasia present. Coincidently, there is a thickening 

 of connective tissue within the papillae, surrounding the blood 

 vessels with a compact mantle of collagen fibrils. More grad- 

 ually the exudate of the corium is removed so that with complete 

 healing the surfaces become flat, but still a little rough and 

 thickened. There is rarely complete ulceration of the surface 

 with destruction of corium ; consequently, scars do not frequently 

 follow healing. 



THE EFFECT OF INTRAVENOUS INJECTION OF NEOSALVARSAN ON 

 THE LESIONS 



Within forty hours after the injection of a therapeutic dose of 

 neosalvarsan all treponemata demonstrable by Levaditi's method 

 disappear from the early fully developed yaw. Within this 

 time also practically all exudation in the lesions subsides. The 

 blood vessels of papillae are rapidly returning to normal, and the 

 excessive fluid, especially within the epidermis, is lost, probably 

 more by surface evaporation than by absorption, so that the 

 lesion shrinks in size. With the loss of exudate the epidermis 



