Elements of biology; a practical Elements of biology; a practical text-book correlating botany, zoology, and human physiology elementsofbiolog00hunt Year: [c1907] EXCRETION 395 exposed part, and thus form pads for special protection. Such thickening of the outer layer is well seen in the pads on the feet of a dog or cat. The inner cells of the epidermis are provided with more or less pigment or coloring matter. It is to the varying quantity of this pigment that the '' light or dark' complexion is due. The inmost layer of the epidermis is made up of small cells which are constantly dividing to
Elements of biology; a practical Elements of biology; a practical text-book correlating botany, zoology, and human physiology elementsofbiolog00hunt Year: [c1907] EXCRETION 395 exposed part, and thus form pads for special protection. Such thickening of the outer layer is well seen in the pads on the feet of a dog or cat. The inner cells of the epidermis are provided with more or less pigment or coloring matter. It is to the varying quantity of this pigment that the '' light or dark' complexion is due. The inmost layer of the epidermis is made up of small cells which are constantly dividing to form new cells to take the place of those in the outer layer which are lost. Sweat-Duct Sebaceous Gland Horny layer Pigment layer Tactile Organs' Nerve— Blood Vessels- Sweat Gland-zS^- Fat > Epidermia ' Dermis Subcutaneous layer Diagram of section of the skin The dermis is largely composed of connective tissue filled with a network of blood vessels and nerv^es. This layer contains the sweat glands, some of the most important glands in the body. Other organs connected with the nervous system and called the tactile corpuscles, cause this part of the skin to be sensitive to touch. ' Nails. — Nails are a development from the horny layer of the epidermis. Except at the tip, the nail lies directly on the dermis, and gets its pink color from the blood beneath it. Nails grow from a layer of living cells at their roots, part of the inner layer of the epidermis. Hairs. — A hair is also an outgrowth of the horny layer, although it is formed in a deep pit or depression in the dermis; this pit is
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