448 REPRODUCTION AND DEVELOPMENT 



true milk. The latter begins to appear about twenty-four hours post- 

 partum and normally becomes abundant within the next day. Nursing 

 should be allowed only once every two hours between six in the morning 

 and the mother's bedtime at night, and only once in the night. After 

 six or seven weeks the two-hour period should be lengthened by a half- 

 hour, and after four months by an hour. Once in three hours is then the 

 most beneficial arrangement for both mother and child, and night-feeding 

 is usually unnecessary after the first four months. As is the case with 

 other neuro-muscular mechanisms (e. g., defecation), the habit of vigorous 

 promptness is important and hence nursing should be accomplished in 

 fifteen or twenty minutes, and from each breast alternately, one breast at 

 a meal. Regularity in taking food is of very essential importance to the 

 child, the danger of feeding too seldom being much less than that of 

 eating too often. 



The mother's best diet for large and adequate milk-production is of 

 the ordinary sort save that it should be generally rather more abundant 

 and richer in proteid (fresh meats) and in liquid. Sufficient muscular 

 exercise out-of-doors is important in maintaining an ample milk-supply. 

 A large proportion of the infants who die in summer from intestinal 

 disease are babies fed on food other than mothers' milk. 



DEVELOPMENT. 



Our concern thus far in describing how the adult racial individuals 

 are reproduced has been largely with the parental part of the process. 

 We have glanced at the operation of the generative mechanism and have 

 discussed the formation of the egg of the new being and the complicated 

 way in which it is made fruitful. Now our view-point changes somewhat. 

 We shall look at things hereafter from the offspring's stand-point and 

 make it our business to outline, if dimly, some of the tangled processes 

 which culminate normally (but how often not!) in the average adult man 

 or woman. Forty weeks of these forty years the new being passes in its 

 mother's womb, and meanwhile is physiologically, even if not morally 

 and legally, a part of its mother's being. This is the fetal life. From 

 the hour of birth until puberty is another period of development, about 

 fourteen years long, and this we may for convenience term childhood. 

 For the next thirty or forty years or less maturity keeps up a somewhat 

 variable level of strength. Beyond this, evolution is apt to become 

 involution, and this period of old age, commencing almost imperceptibly, 

 ends inevitably in death. Contrasting the human adult with the once- 

 divided ovum, one realizes what "development" means. Only an 

 expert embryologist could tell the human ovum at this stage from that 

 of any of a thousand other species, yet the adult man or woman has a 

 physical and psychical nature which is unique and, taken as a whole, 

 the summit of organic evolution on the Earth. This is so, however, not 

 because the protoplasm on which this nature is somehow based is superior 



