7th. Pustulæ: Pustules. These differ from vesicles in that the central exudate becomes the seat of suppuration and a limited collection of pus, at first central, though later involving, it may be the whole area of the exudate. It is often merely an advanced stage of the papule or vesicle. We find examples in the different forms of variola, in lesions caused by tartar emetic or croton oil, and in several forms of dermatitis. It is essentially microbian.
8th. Furunculus: Furuncle: Boil. Inflammatory nodosity of the derma, resulting in a necrotic central core and suppuration. Is bacteridian and common on the coronet and lower parts of the limbs in solipeds.
9th. Carbunculus: Carbuncle. An inflammatory nodosity or cluster of nodes of much greater extent, tending to necrotic change and sloughing over a much more extending area. Microbian.
10th. Squama: Scales: Dandruff. Exudation products and cells dessicate and exfoliate as branlike scales or thicker coherent laminæ. Examples are found in psoriasis, pityriasis, eczema, variola, rinderpest, etc.
11th. Crustæ: Crusts: Scabs. Hard, solidified masses of epidermis, blood, pus and serous exudate.
12th. Callositas: Callosity. Abnormal thickening of the epidermis, as a physiological protective cell growth. Examples: pads on the knees of camels, cows and even horses from kneeling on a hard, uneven surface.
13th. Sitfasts: Necrotic Callosities. Combination of dried up exudate of horny consistency, and a thickened, fibroid and partially necrotic portion of the subjacent derma with little or no disposition to spontaneous detachment.
14th. Cornu Cutaneum: Keracele: Horny Growth. Abnormal horny growth from keratogenous tissue, or from the derma in its vicinity or at some other point of the skin.
15th. Erosions: Abrasions. Lesions of the cuticle exposing the true skin, and the result of itching, scratching, friction, biting or other mechanical or thermic injury.
16th. Rimæ: Cracks: Chaps. These are linear breaches often confined to the epidermis in the bends of joints, under congestion and suppression of sebaceous secretion, in elephantiasis, dropsy, petechial fever, etc. Unless they have ulcerated they may heal without cicatrix.