582 THE HUMAN BODY 



only dirty but swarming with micro-organisms. In cities it has 

 become the practice for medical societies to inspect various dairies 

 and set their seal of approval upon those that fulfil the sanitary 

 conditions essential to the production of pure, clean milk. The 

 slightly higher cost of such " certified" milk should not be allowed 

 to bar it from homes where children are to be fed except where 

 extreme poverty makes its procurement impossible. In small 

 towns and in the country personal inspection of the source of 

 the milk supply on the part of parent or physician should give 

 assurance of its cleanliness. Where it is impossible to procure 

 milk free from suspicion, pasteurization (heating to 120 F. for 

 20 minutes) should be resorted to. This destroys most of the 

 dangerous organisms, but of course is not a complete substitute 

 for cleanliness and care in the production of the milk in the be- 

 ginning. 



In the first weeks after birth it is no use to give an infant starchy 

 foods, as arrowroot. The greater part of the starch passes through 

 the bowels unchanged; apparently because the pancreas has not 

 yet fully developed, and has not commenced to make its starch- 

 converting enzym. Later on, starchy substances may be added 

 to the diet with advantage, but it should be borne in mind that 

 they cannot form the chief part of the child's food; it needs pro- 

 teins for the formation of its tissues, and amyloid foods contain 

 none of these. Many infants are, ignorantly, half starved by 

 being fed almost entirely on such things as corn-flour or arrowroot. 



Puberty. The condition of the reproductive organs of each 

 sex described in preceding pages is that found in adults; although 

 mapped out, and, to a certain extent, developed before birth and 

 during childhood, these parts grow but slowly and remain func- 

 tionally incapable during the early years of life; then they com- 

 paratively rapidly increase in size and become physiologically 

 active; the boy or girl becomes man or woman. 



This period of attaining sexual maturity, known as puberty, 

 takes place from the eleventh to the sixteenth year, and is accom- 

 panied by changes in many parts of the Body. Hair grows more 

 abundantly on the pubes and genital organs, and in the armpits, 

 in the male also on various parts of the face. The lad's shoulders 

 broaden ; his larynx enlarges, and lengthening of the vocal cords 

 causes a fall in the pitch of his voice; all the reproductive organs 



