436 MEDICAL MYCOLOGY 



regions in folds (e.g., eczema marginatum of the inguinocrural fold and the 

 interdigital spaces) and those on the very thick horny layer of the palmar and 

 plantar surfaces. 



On the drier portions of the epidermis, there are two types, one dry and 

 scaling, the other vesiculose, rarely pustulose. Each produces a circular 

 lesion which may become a ring after the central area has healed spontane- 

 ously. The fungus is most abundant and active at the margin of the advancing 

 lesion, hence scales or vesicles from this area are most suitable for study. 

 Infection is frequent in the uncovered portions of the body as might be ex- 

 pected, since many of the sources of infections are domestic animals. One 

 case has been reported on the anus. The infection may be either a single large 

 lesion, or rather generalized and exanthematous by subsequent inoculation of 

 other portions of the epidermis from the original lesion or as a result of 

 allergic phenomena. (See p. 474.) 



In the first or scaling type, the lesion begins as a small red slightly ele- 

 vated spot which spreads. The central portion is covered with small scales, 

 occasionally larger and almost psoriasiform, while the margin remains red. 

 The amount of redness varies from not much more than that of pityriasis 

 versicolor, to quite red and slightly swollen lesions. Occasionally a few 

 evanescent vesicles are formed. 



In tinea imbricata from India, Ceylon, Southei"u China from Szechwan 

 to Formosa, and from the Malay Archipelago, the lesion first appears as small 

 vesicles, which dry. The epidermis peels back in triangular flakes with one 

 free angle toward the center of the lesion and the opposite side attached to 

 the sound skin. New rows of vesicles at the periphery continue to develop 

 new triangular scales, often producing patterns of considerable intricacy, 

 especially if the initial infections were approximately symmetrical. The 

 palmar and plantar surfaces are not attacked; the scalp, the scrotum, and 

 moist folds of the skin, very rarely. The hair is never infected. Jouveau- 

 Dubreuil (1919) suggests that infection is caused by scratching or enters 

 through an open sore rather than by simple contact. The disease is appar- 

 ently of many years' duration, not healing spontaneously. 



In the second or vesiculopustular type, vesicles arise either irregularly or 

 in a ring just back of the margin which is hyperemic and edematous. The 

 formation of a crust is followed by spontaneous healing from the center out- 

 ward. Pigmentation of the skin increases at the center and varies with the 

 normal amount of pigment in the skin. Occasionally pustules form, but this 

 usually significes infection of the hair follicle ; therefore we shall study these 

 along with lesions involving follicle and hair. Scratching, following the 

 pruritus which often accompanies the lesions, may lead to lichenification or 

 to secondary infections. Hyphae and chains of arthrospores are usually de- 

 monstrable in the scales. When this type becomes chronic (Podwyssotzkaja 

 & Rosenthal 1933) it is often located on the knee or elbow, spreading upward 

 and downward to the adjacent regions of the leg and arm. It may also start 



