. The Ontario public school hygiene . oowarm. It comes away alsowhen we are not warm at may prove this for your-selves by placing your handup to the wrist in a large wide-mouthed bottle. The bottlemust be dry and cool. Ina half minute or less a littlemist forms on the inside of thebottle. This is the invisiblesweat which is coming fromthe small pores or openings in the skin of the we should cut open one of these pores and examineits inner end with a magnifying glass, we should find thesmall rounded body which made the sweat. It is calleda sweat-gland. There are probably between
. The Ontario public school hygiene . oowarm. It comes away alsowhen we are not warm at may prove this for your-selves by placing your handup to the wrist in a large wide-mouthed bottle. The bottlemust be dry and cool. Ina half minute or less a littlemist forms on the inside of thebottle. This is the invisiblesweat which is coming fromthe small pores or openings in the skin of the we should cut open one of these pores and examineits inner end with a magnifying glass, we should find thesmall rounded body which made the sweat. It is calleda sweat-gland. There are probably between one andtwo millions of these glands in the human skin. Thequantity of sweat given off from them daily is very great,varying between one and four pints. It is very difficultto measure the quantity exactly, because it varies fromtime to time with the kind of food, the quantity of fluiddrunk, the temperature of the air, the season of the year,and the work done by other organs besides the sweat-glands, such as the lungs and the Figure 28.—The hand in a bottleshowinjj moisture fonning fromthe sweat-pores. THE SKIN 67 About one-third of an ounce of the daily output ofsweat is salt and other substances, the rest being, ofcourse, water. With the watery part of sweat we are notat present concerned ; but, as we shall see later, its chiefuse is to keep us cool when we are too warm. Whenthis watery part dries up it leaves behind it on thesurface of the skin the salt and other substances ofwhich we have just spoken. Water, on the other hand,which has been spilt upon the floor dries up, weknow, and disappears, but pure water leaves no tracebehind it. Where does this solid matter in sweat come from?In answer, it may be said that the sweat-glands obtainit from the blood, and the blood obtains it from theflesh, bone, nerves, and other parts of the body. The salt and other matter in the sweat is in factdead stuff which the blood gathers up from all over thebody and carries to the sw
Size: 1453px × 1719px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdec, booksubjectchildren, booksubjecthygiene
