The Pedestrian's Record

96 the pedestrian's record. explained by the constitutional difference between the two ; the general system of the one has arrived at its ultimate growth, whilst the system of the other is busily engaged in the construction of its various corporeal tissues, and which prolonged sleep evidently favours. The adult does not require the slumber necessary for an infant, because the growth ofhis body has ceased, and the due balance between waste and supply has to be kept up, the constructive only has to keep pace with the destructive ; whereas the infant's body represents a partially-formed fabric striving at further growth about to terminate in its complete construction ofthe full-grown man. During the period of uterogestation the foetus passes through a prolonged sleep ; when the functional energy is devoted to the construction of those organisms which together constitute the infant's body. After birth, the babe sleeps day and night, and seems only to awake to obtain sustenance, and sleeps again imme­ diately after having received it. This proves how actively the organic functions are engaged in con­ struction, and more so as age increases, the periods of slumber lessen gradually from year to year, i.e., as the constructive and destructive forces become more equally balanced, the necessity for prolonged sleep gradually ceases, until complete development has been attained in the person of the adult. The excess of the constructive force over the destructive is not only marked during infancy, but also through child­ hood to adultism ; the youth requires more sleep than