Vesiculæ, or vesicles, are small, circumscribed elevations of the scarf-skin, containing serum, at first (both in their coats and contents) transparent, afterwards white and opaque, and terminating in the formation of scurf or thin scales. Under this head are ranged varicella (chicken-pox), sudamina, eczema (red fret), herpes (fret), scabies (itch).