Pathology.—In order clearly to comprehend the pathology of sycosis it is of advantage to consider the structure of hair, the mode of its growth and nutrition.
Hair is a modification of the epithelial layer of the integument. The root of each hair is lodged in a little pit called the hair follicle. The follicle descends through the substance of the skin into the subcutaneous connective tissue. Its orifice is shaped like a funnel, the narrower and lower end of the funnel being known as the neck. Below the neck the follicle widens and terminates in a bulbous expansion. The proper wall of the hair follicle belongs to the corium and is divided into three layers: an outer, a middle and an internal. The outer is the thickest and consists of connective tissue fibres disposed parallel to the long axis of the follicle. It supports a small artery and vein and