16 
ORDER BIMANA^GENUS HOMO. 
THE PHYSICAL DEVELOPMENT OF MAN. 
BIRTH AND INFANCY. 
The number of offspring in the human species is usually one at 
each parturition, and twins do not occur more frequently than once 
in five hundred accoucheinents. Birtl^s, 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, 
eleven 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 which 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 e.\istence 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 haimorrhage 
is not alw'ays the consequence of this neglect, and the Hottentot women 
do not even remove the slight mucous fiuid 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 anciently 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 effected 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 portae, and is distributed throughout the body by the aorta and its 
branches. Before this period the blood p.assed 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 alter birth. Its 
eyes are dull, wrinkled, and covered with a slight membrane (iumca 
Ilallcrf), which prevents the too violent action of the light upon these 
still delicate 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 culosirum, is 
serous and laxative, and serves to clear the intestines of the meconium, 
or blackish fluid, which is discharged dining 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. 'Fhere 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 infant 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 jiajm, mannna, 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 bo 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 comple.xions are born rather 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. 
PUBERTY. 
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 which 
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 they become so, from their 
exposuie to the excessive cold of their climate ; the women also are not 
marriageable until seventeen cr even nineteen. On the other hand, in 
Hindoostan, Persia, and Arabia, the males are cap.able 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 influeuce. 
Among the white races of Europe, these variations are very consider- 
able, especially in respect to the females. Thus, in Saxony, Thuringia, 
and Upper Germany, the women are not marriageable before fifteen even 
in the towns, and they arc still slower in countries ly'ing farther to the 
north, or in elevated places, where they are sometimes delayed until the 
ages of twenty to twenty-four. For this reason, the females in the 
islands of the North, the Orkneys, and the 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 the large towns, where various causes combine, and in- 
duce a greater degree of precociousness. In Italy, the women are formed at 
twelve years of age; and it is thesamein Spain; while at Cadiz, marriages fre- 
quently take place at that age. In Minorca, eleven is the period of puberty ; 
and at Smyrna, mothers have been seen at eleven or twelve. The 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 the 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 the usual marriageable period, not 
only in Arabia, but also in most parts of Africa. 
Many instances are quoted of an equally great precociousness being 
observed on the Malabar Coast, where the fern-ales 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 
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 
the period of puberty. In fttet, a common custom prevails in India, <ur 
the inhabitants to betroth and even to marry their children together , fur 
which reason, girls have been known in Java and Hindoostan to he 
mothers at ten years of age. 
These instances are not, however, very general, and remarkable ex- 
ceptions of the same kind are often observed in the temperate regions o 
Europe. Thus, Haller saw Swiss girls of twelve years, and Smelhe, 
English girls of the same age, e.xhibiting the usual signs of puberty. 
Belgium and Switzerland, girls have produced at nine years of age; hu- 
nothing general should be inferred from these solitary cases. 
