. Biology and human life. Biology. THE HUMAN ORGANISM 287. although the amount of vitamin in the milk of a mother or of a cow depends upon the diet of the milk-producer. It has also been found that cod-liver oil is useful in many cases, be- cause it contains a relatively large amount of vitamin A/ But here again a great deal depends upon how the cod-liver oil is prepared, for experiments show that some brands are very effective, w^hile others are almost worthless (see Fig. 142). Posture may have a direct bearing upon the vital organs: cramping positions interfere with breathing, with the actio
. Biology and human life. Biology. THE HUMAN ORGANISM 287. although the amount of vitamin in the milk of a mother or of a cow depends upon the diet of the milk-producer. It has also been found that cod-liver oil is useful in many cases, be- cause it contains a relatively large amount of vitamin A/ But here again a great deal depends upon how the cod-liver oil is prepared, for experiments show that some brands are very effective, w^hile others are almost worthless (see Fig. 142). Posture may have a direct bearing upon the vital organs: cramping positions interfere with breathing, with the action of the stomach, with the bowels, and, less directly, with the heart, since they may influence the ac- tivity of the larger muscles, and so the circulation of the blood (see Fig. 143). Good posture is thus important, not only for the sake of appearance but for the, sake of comfort and efficiency. When a bone is broken, new bone cells begin to form from the periosteum, and the space is gradually filled in with solid bone. It is therefore important that the broken ends (i) be set together accurately and (2) be kept in position until the new formation is strong enough to bear the strains of ordinary activity. In cases of dislocation early replacement is necessary. Caution must be taken against (i) movements that may bruise or tear muscles, tendons, or 1 Experiments on guinea pigs and white rats, as well as observation on young babies, tend to show that the effect of the vitamin A is in many ways identical with the effects of exposure to sunlight. It would seem that the ultra- violet rays (those portions of the sunlight that appear beyond the violet rays in a spectrum) have an important bearing upon the way protoplasm works over lime and that the presence of vitamin A produces similar results. Accord- ing to some of the experiments it may even be that the ultra-violet rays are somehow "stored" in food and later made active in the body. Fig. 141. Incomplete skull of infan
Size: 1747px × 1431px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookpublishe, booksubjectbiology
