16 



ORDER BIMANA.— GENUS HOMO. 



i 



THE PHYSICAL DEVELOPMENT OF MAN. 



BIIITH AND INFANXT. 



The number of offspring iti the human species is usually one at 

 each parturition, and twins do not occur more frequently than once 

 in five hundred accoucheinents. Births, in which a greater num- 

 ber is produced, occur still more rarely. Gestation continues for 

 nine months. A foetus of one month old is usually an inch in 

 length; of two months, two inches and a quarter; of three months, 

 five inches; of five months, six or seven inches ; of seven months, 

 Pleven inches; of eight months, fourteen inches; of nine months, 

 eighteen inches. Infants born at a less period than seven months 

 very seldom survive. 



The milk-teeth begin to appear some months after birth, com- 

 mencing by those in front. There are twenty at the age of two 

 years (see the Dentary Formula), all of which fall successively to- 

 wards the seventh year, to be replaced by others. Of the twelve 

 back molars wiiich do not fall, four appear at the age of four 

 and a half, four at nine years, and the last four do not sometimes 

 appear until near the twentieth year. 



The foetus grows more and more in proportion as it approaches 

 the period of birth ; — the infant, on the contrary, grows at a less 

 rapid rate as it advances in years. At the period of birth, it is more 

 than a quarter of its ultimate height ; it has reached the half at the age 

 of two years and a half; and the three quarters at nine or ten years. 

 The first cries of the newly-born infant indicate the uneasiness of its 

 change from the one mode of existence to the other. On its first ap- 

 pearance it is washed in tepid water, and dried ; its umbilical cord is tied, 

 and cut above the ligature. The women in savage countries bite this 

 cord through with their teeth, and do not always tie it, yet hsEmorrhage 

 is not always the consequence of this neglect, and the Hottentot women 

 do not even remove the slight mucous fluid left upon the skin. Among 

 several nations of the North, it is customary to plunge the newly-born 

 infants into cold water, or even to roll them in the snow. This practice 

 was ••xnciently adopted by the Scotch, Irish, Helvetians, and Germans. 

 In our own times, it is still practised by the Morlachs, Icelanders, Sibe- 

 rians, and several others ; and, though it sometimes hardens the cellular 

 tissue, renders it violet-coloured, and causes them to perish, yet it has 

 the effect of accustoming the survivors to the cold at an early age, and 

 induces a more robust habit of body. At the moment of birth an import- 

 ant change is efl^ected in the circulation of the blood. The air rushes 

 into the lungs, and the blood which fills these viscera returns to the heart by 

 the vena portse, and is distributed throughout the body by the aorta and its 

 branches. Before this period the blood passed immediately from the right 

 to the left ventricle of the heart. The infant at birth is still cartilaginous. 

 Its limbs are small ; its flesh soft, gelatinous, and moist. Its vessels are 

 large and wide; the brain considerable; the belly distended ; the cellular 

 tissue surrounding its organs loose, spongy, and filled with lymph ; its 

 glands swollen and filled with watery fluid. A milky fluid can some- 

 times be squeezed from its breasts during the first days after birth. Its 

 eyes are dull, wrinkled, and covered with a slight membrane (tunica 

 Halleri), which prevents the too violent action of the light upon these 

 still dehcate organs. The ears are closed by a mucous fluid, which pre- 

 vents the admission of loud sounds. The pituitary sinuses of the nose 

 are obstructed by a viscous humour, so as to be incapable of smell ; the 

 skin is too soft to convey any sensations of touch ; and the tongue can 

 scarcely taste anything. The use of the senses is acquired gradually ; 

 and instinct alone directs the infant mechanically towards its mother's 

 breast, and instructs it to suck. 



At birth, the infant is about twenty inches in length, and weighs 

 from six to ten pounds. The first milk of the mother, or colostrum, is 

 serous and laxative, and serves to clear the intestines of the meconium, 

 or blackish fluid, which is discharged during the first day after birth ; yet 

 the infant is commonly delayed for twelve hours before it is permitted to 

 be fed. Nature has wisely adapted the qualities of the mother's first milk 

 to the wants of the infant. The milk of nurses is much less suitable, 

 being too old and substantial, for it is more serous in the mother in pro- 

 portion as it approaches the period of birth. At all times, the milk of 

 a stranger is not so well adapted to the temperament of the infant as that 

 of its own mother, and the milk of any other animal is still more objection- 

 able. There is nothing so judicious in these matters as a scrupulous 

 attention to the suggestions of Nature. 



The newly-born infant sleeps almost continually, and requires the 

 breast every time it wakes. The Negro infant clings to the long breast of 

 its mother, and holds itself so firmly to her back, that she can attend to 

 her other labours without the trouble of supporting it upon her arms. 

 Towards the fourteenth day the iul'an'; begins to smile and recognize those 



who approach it; but it does not attempt to speak until about the tenth 

 or twelfth month. The words most easily pronounced are composed of 

 labial consonants, such as papa, mamma, baba, and these have, therefore, 

 served in most languages to denote the same objects. 



For the first three months after birth, no other food should be given 

 to the infant than the milk of its mother; afterwards, several nutritious 

 substances, easy of digestion, may also be employed. The natural period 

 for discontinuing the milk is commonly on the appearance of the first 

 teeth. The incisive teeth, eight in number, being four in the front of 

 each jaw, appear at the age of eight or ten months. Their growth is 

 painful, and is announced by fever and inflammation. At this critical 

 period, very little food should be given to the infant. The order in which 

 the teeth exhibit themselves has already been explained (See pages 86, 

 87). Infants are sometimes born with their front teeth ; but these ex- 

 amples are very rare. 



The hair of newly-born infants is always more or less fair in the Eu- 

 ropean variety, but in other races of Man it is already quite black. The 

 same remark applies to the iris ; and the colour both of the hair and eyes 

 becomes deeper as they advance in years. The infants of Negroes, and 

 persons of dark complexions are born rath er of a lighter tint, but they be- 

 come gradually darker and darker, although they are not exposed to the 

 rays of the sun. The growth of girls is usually more rapid than that of boys, 



PUEERTY. 



In our climates, the human species exhibits the first signs of puberty 

 from the ages of twelve to fourteen in girls, and from fifteen to seventeen 

 in boys ; but these periods vary all over the globe. They seem to depend 

 upon the temperature of the climate, the quantity and quality of the food, 

 the general purity of morals, the temperament of the individuals, their 

 employments, as well as the peculiar constitution of the races to wdiich 

 they belong. 



Heat, as is well known, tends to increase the activity of the vital power 

 in all organized bodies ; and ought, consequently, by hastening their growth, 

 to bring the period of puberty nearer to that of birth. An inhabitant of 

 Finland or Iceland is scarcely marriageable at eighteen years of age, and 

 some are even as old as twenty-two before thej' become so, from their 

 exposure to the excessive cold of their climate ; the women also are not 

 marriageable until seventeen or even nineteen. On the other band, in 

 Hindoostan, Persia, and Arabia, the males are capable of marrying at the 

 age of thirteen or fourteen, while girls are often mothers at ten or twelve. 

 Intermediate climates may accelerate or retard the puberty of the people 

 exposed to their influence. 



Among tbe white races of Europe, these variations are very consider- 

 able, especially in respect to the females. Thus, in Saxony, Thuringia, 

 and Upper Germany, tbe women are not marriageable before fifteen even 

 in the towns, and they are still slower in countries lying farther to the 

 north, or in elevated places, where they are sometimes delayed until tbe 

 ages of twenty to twenty-four. For this reason, the females in the 

 islands of the North, tbe Orkneys, and tbe Western Islands, preserve 

 their fecundity to an advanced age. In Ireland, sixteen appears to be 

 the usual period ; in France, it is fourteen or even thirteen in the southern 

 departments or tbe large towns, where various causes combine, and in- 

 duce a greater degree of prccociousness. In Italy, the women are formed at 

 twelve years of age; audit is the same in Spain; while at Cadiz, marriages fre- 

 quently take place at that age. In Minorca, eleven is tbe period of pubert}'; 

 and at Smj'rna, mothers have been seen at eleven or twelve. Tbe Per- 

 sian women are marriageable at nine or ten ; and nearly the same thing 

 takes place at Cairo. The Berber women are often mothers at eleven, 

 according to Shaw ; also tbe Agows of Abyssinia, according to Bruce. 

 From nine to ten, they appear to be marriageable at Senegal, according 

 to Adanson. The age of ten years is tbe usual marriageable period, not 

 only in Arabia, but also in most parts of Africa. 



Many instances are quoted of an equally great prccociousness being 

 observed on tbe Malabar Coast, where the females are married at eight 

 to ten years, and become mothers soon afterwards. .In the Deccan, 

 according to Thevenot, women have been known to have children at 

 eight years of age. Paxman has seen married children from four to six 

 years of age ; but it is impossible to believe that these could have reached 

 tbe period of puberty. In fact, a common custom prevails in India, for 

 tbe inhabitants to betroth and even to marry their children together , for 

 which reason, girls have been known in Java and Hindoostan to be 

 "aiiothers at ten years of age. 



These instances are not, however, very general, and remarkable ex- 

 ceptions of the same kind are often observed in tbe temperate regions of 

 Europe. Thus, Haller saw Swiss girls of twelve years, and Sniellie, 

 English girls of the same age, exhibiting the usual signs of puberty. In 

 Belgium and Switzerland, girls have produced at nine years of age; but 

 nothing general should be inferred from these solitary cases. 



