[CHAPTER XXXIX.]
PERSONAL HYGIENE (continued)—CLEANLINESS.
Physiological Considerations.—The skin consists of a superficial part or epidermis, and a deeper part called the dermis or cutis.
Tubes of two kinds open on the surface of the skin, penetrating at their deeper ends into the cutis, viz. sweat or sudoriparous glands and sebaceous glands. The sudoriparous glands are simple tubes, the lower ends of which lie coiled up in the dermis. Each tube when straightened out is about a quarter of an inch long. It has been estimated that in the palm of the hand there are 3,528 orifices of sudoriparous and sebaceous glands on a square inch of surface; reckoning each gland at ¼; inch long, this means 73½ feet of tubes in this small space. Assuming that there are 2,800 tubes to every square inch, and that the amount of surface in a man of ordinary height and bulk is 2,500 square inches, it follows that there are seven million pores in a man—that is, 1,750,000 inches, or nearly twenty-eight miles.
The perspiration secreted by the sudoriparous glands is constantly evaporating from the surface of the body. It is very important that the orifices of these glands should be kept open in order that the secretion may not be interfered with. Animals have been killed by covering their skin with gelatine, and so preventing the escape of perspiration.
The sebaceous glands are shorter than the sudoriparous, and commonly end alongside the hairs before the latter issue from the skin. They secrete an oily material which serves the purpose of a natural pomade. The sebaceous secretion also keeps the general surface of the skin unctuous and supple. The smell of the sebaceous secretion may be unpleasant, especially in the arm-pits and some other parts. Frequent washing is therefore desirable.
The Conditions Due to Uncleanliness are due to obstruction of the excretory ducts, to accumulation of débris on the general surface of the skin, and to the consequent interference with the circulation.
1. The obstruction of the sudoriparous pores of the skin interferes with the elimination of waste products by the perspiration; these are re-absorbed or retained in the system; consequently more work is thrown on the lungs and kidneys, and the equilibrium of health is destroyed.
Sebaceous obstruction causes an accumulation of oily secretion in the ducts. The black spots so commonly seen about the nose, are the blocked up orifices of sebaceous glands, and by squeezing the nose tiny threads of fatty matter are forced out from the interior of these glands. Pimples on the face are usually due to obstruction of the sebaceous glands; sometimes the obstruction leads to inflammation around the sebaceous gland (acne) which often permanently injures the skin.
2. Accumulation of effete matter on the skin occurs, unless frequent ablutions are performed. The epidermis is constantly shedding its older and more superficial parts, in the form of minute scales or “scurf.” In the absence of frequent washing, the scales of epithelium tend to accumulate, the sebaceous secretion matting the scales together, and rendering them more adhesive. The saline matters of the perspiration also accumulate along with the scales and sebaceous secretion, and in virtue of their hygroscopic properties tend to keep the skin clammy and cold.