The development of the human body; a manual of human embryology . diminished, and these changes react moreor less profoundly on all parts of the body. Hence, al-though the post-natal development consists chiefly in thegrowth of the structures formed during earlier stages, yetthe growth is not equally rapid in all parts, and indeed insome organs there may even be a relative decrease in this is true can be seen from the annexed figure (), which represents the body of a child and that of anadult man drawn to the same scale. The greater relativesize of the head and upper part of t
The development of the human body; a manual of human embryology . diminished, and these changes react moreor less profoundly on all parts of the body. Hence, al-though the post-natal development consists chiefly in thegrowth of the structures formed during earlier stages, yetthe growth is not equally rapid in all parts, and indeed insome organs there may even be a relative decrease in this is true can be seen from the annexed figure (), which represents the body of a child and that of anadult man drawn to the same scale. The greater relativesize of the head and upper part of the body in the child isvery marked, and the central point of the height of the 501 502 THE DEVELOPMENT OF THE HUMAN BODY. child is situated at about the level of the umbilicus, whilein the man it is at the symphysis pubis. This excessivedevelopment of the upper portions of the body of the childis largely due to the nature of the blood-supply duringfetal life, when, as may be seen by reference to Fig. 152,the blood passing to the head, neck, arms and upper por-. Fig. 266—Child and Man Drawn to the Same Scale.—(Longer, fromthe Growth of the Brain, Contemporary Science Series, by permissionof Charles Scribners Sons.) tions of the thorax leaves the aorta before the ductusarteriosus opens into it, and is therefore practically un-mixed with venous blood, while throughout the rest of thebody the supply is largely diluted with blood from theright side of the heart. That there is a distinct change in the geometric form of POST-NATAL DEVELOPMENT. S03 the body during growth is also well shown by the follow-ing consideration (Thoma). Taking the average heightof a new-born male as 500 mm., and that of a man ofthirty years of age as 1686 mm., the height of the bodywill have increased from birth to adolescence \6-^ = The child will weigh kilos and the man , and if the specific gravity of the body with the in-cluded gases be taken in the one case as and in theo
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
