The screaming of infants consists of prolonged expirations, with short
and rapid, almost spasmodic inspirations, followed at a somewhat more
advanced age by sobbing. According to Gratiolet,[611] the glottis is
chiefly affected during the act of sobbing. This sound is heard at the
moment when the inspiration conquers the resistance of the glottis, and
the air rushes into the chest. But the whole act of respiration is
likewise spasmodic and violent. The shoulders are at the same time
generally raised, as by this movement respiration is rendered easier.
With one of my infants, when seventy-seven days old, the inspirations
were so rapid and strong that they approached in character to sobbing;
when 138 days old I first noticed distinct sobbing, which subsequently
followed every bad crying-fit. The respiratory movements are partly
voluntary and partly involuntary, and I apprehend that sobbing is at
least in part due to children having some power to command after early
infancy their vocal organs and to stop their screams, but from having
less power over their respiratory muscles, these continue for a time to
act in an involuntary or spasmodic manner, after having been brought
into violent action. Sobbing seems to be peculiar to the human species;
for the keepers in the Zoological Gardens assure me that they have
never heard a sob from any kind of monkey; though monkeys often scream
loudly whilst being chased and caught, and then pant for a long time.
We thus see that there is a close analogy between sobbing and the free
shedding of tears; for with children, sobbing does not commence during
early infancy, but afterwards comes on rather suddenly and then follows
every bad crying-fit, until the habit is checked with advancing years.
_On the cause of the contraction of the muscles round the eyes during
screaming_. We have seen that infants and young children, whilst
screaming, invariably close their eyes firmly, by the contraction of
the surrounding muscles, so that the skin becomes wrinkled all around.
With older children, and even with adults, whenever there is violent
and unrestrained crying, a tendency to the contraction of these same
muscles may be observed; though this is often checked in order not to
interfere with vision.
Sir C. Bell explains[612] this action in the following manner: During
every violent act of expiration, whether in hearty laughter, weeping,
coughing, or sneezing, the eyeball is firmly compressed by the fibres
of the orbicularis; and this is a provision for supporting and
defending the vascular system of the interior of the eye from a
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