If a man or woman have a plague upon the head or the beard;
a dry scall, х neteq (H5424); Septuagint, thrausma], when the leprosy was distinguished by being in sight deeper than the skin, and the hair became thin and yellow х tsaahob (H6669), gold-coloured].
'So very variable are the appearances which this disease produces on the head affected by it, that it has received no less than 20 different names. It is most commonly known under the scientific names of porrigo, herpes, alopecia (baldness), tinea, and popularly as scald head and ringworm. Some forms of it attack children almost exclusively, and are found only among the poor, where there is not sufficient attention to cleanliness; while others occur at all ages, and in all ranks and conditions of society. The effects which it produces are no less variable than its forms, ranging from the small, brown, scurfy spots which at a certain period cover the head of every child, and which a few vigorous applications of soft soap and water will remove, to those extreme cases where it disorganizes the whole order of the scalp, and seriously affects the general health. Its varying appearances and effects are in all likelihood caused by the different stages of development of the parasitic plant (the Achorion Schonleinii) which produces all these abnormal appearances on the human head, by its greater or less abundance on the parts affected, and the more or less favourable circumstances in which it is placed. The form which it most frequently exhibits is that of rounded patches of thick yellowish scales, marked by numerous depressions, at first very small, but gradually increasing and invading larger surfaces. The hairs on the parts affected are dull, dry, and colourless, exceedingly brittle, and easily extracted, broken off close to the skin, and covered with greyish-white dust. It is described with sufficient accuracy in this passage of Leviticus.
Examined under the microscope, the hairs are found to be considerably swollen, with nodosities here and there, produced by masses of sporules or seeds embedded between the longitudinal fibres. The bulbs are flattened or destroyed altogether; the ends have a very ragged appearance, resembling in miniature the ends of a piece of wood, which has been broken across; while the medullary portion, or the pith, of the hair is quite disorganized, owing to the pressure of the plant, which appears enveloping; it, either as isolated spores or as chains of cells. The disease may last an indefinite length of time, but it usually terminates in the obliteration of the hair-follicles and permanent baldness of the affected parts. It is far more severe in foreign countries than in this-instances being numerous where it has completely removed the hair from the whole head, eyebrows, and beard, leaving them completely smooth and naked, impairing the constitution when so extensively developed, and when children are the subjects, arresting their growth. A very formidable type of it occurs in Poland under the name of Plica polonica. But it is particularly malignant in the warm countries of the South and East. The manners and occupations, as well as the food of the inhabitants are peculiarly favourable to the production of those abnormal growths, while the heat and moisture of the climate push them into excessive development (see 'Des Vegetaux qui croissent sur l'Homme, et sur les Animaux vivants,' by M. Robin, Paris, 1862; a review of this work, and two articles entitled 'Human Vegetation,' Macmillan's Magazine, vol. 6:, May-Oct., 1862).