In the natural course, when the hair has attained a certain growth, it is thrown off, and its place supplied by a new growth formed from the pulp within the hair follicle. This process is continually going on, and is analogous to the shedding of the coat in quadrupeds, or the moulting of birds at certain seasons. The German physiologists, whose arduous and persevering labours in scientific research have never been excelled, have investigated with rare industry the minutest details respecting the growth of the hair; and one of them has accomplished the task of counting the number of hairs in heads of four different colours. In a blond one he found 140,000 hairs; in a brown, 109,440; in a black, 102,962; and in a red one, 88,740. Erasmus Wilson states that the superficial surface of the scalp may be taken at 120 inches, he averages the number of hairs per inch at 1000, which gives 120,000 for the entire head. It will be seen from the greater fineness of the blond hairs that the number is greater than those of red or black hair, and that red is the coarsest. The silken fineness of some shades of light hair is very remarkable, even the poets are evidently put to their wits end adequately to express its extreme fineness and beauty,--it is likened to the golden beams of day--and who has not seen the light playing upon it, and streaming rays and sparkles of lustrous beauty given out, as it were, from a diffused wave of sunshine-- “And on her hair a glory, like a saint.” It is not clearly shown to what we must attribute the disposition to curl, which some hair naturally possesses. Some have thought that it was owing in a great measure to the presence of a considerable amount of oily matter in the shaft of the hair, which hinders the animal matter from attracting moisture which would have a tendency, it is said, to straighten the hair. But the more probable and more general opinion is that it mainly arises from the flatness of the hair. Now this flattening is sometimes very considerable, and the diameter of the hair two-thirds broader in one direction than in the other. The hair of the beard and whiskers exhibits the peculiarity most distinctly. In proportion to its size, the strength of a hair is very remarkable; one from a boy supported a weight of 7,812 grains; another from a man, 14,285 grains. The elasticity of the hair is very apparent, a hair 10 inches long has been stretched to 13 inches; and a hair stretched one-fifth of its entire length returns, with but trifling excess, to its first dimensions.