In some children, in the first two years of life, we find a definite and measurable increase in the irritability and conductivity of the peripheral nerves.  The strength of current necessary to produce by direct stimulation of the nerve a minimal twitch of the corresponding muscle may be many times less than the normal.  Of this heightened irritability of the nervous system, to which the name “spasmophilia” has been given in America and on the Continent, the most striking symptom is a liability alike to tetany or carpo-pedal spasm, to generalised convulsions, and to laryngismus stridulus.  In addition, in most cases it is generally possible to demonstrate the presence of Chvostek’s sign and of Trousseau’s sign.  Chvostek’s sign consists in a visible twitch of the facial musculature, especially of the orbicularis palpebrarum or of the orbicularis oris, in response to a gentle tap administered over the facial nerve in front of the ear.  Trousseau’s sign is the production of tetany by applying firm and prolonged pressure to the brachial nerve in the upper arm.  The aetiology of spasmophilia is still a matter for dispute, but the evidence which we possess is in favour of the view that we have here to deal with a disturbance of calcium metabolism.  The calcium content both of the blood and of the central nervous system has been shown to be much lowered.  It is in keeping with this that clinically we note how frequently spasmophilia and rickets occur in the same child.  In some families the condition recurs through many generations.

For our present purpose—­the examination of some common neuroses of nursery life—­it would be out of place to enter into a detailed consideration of this disorder of spasmophilia as a whole.  The symptom of laryngismus stridulus—­the so-called breath-holding—­alone need concern us, and that for a special reason.  The spasm of the glottis is produced under the influence of any strong emotion—­in anger, for example, or in fear, in excitement or in crying for any reason.  To control or prevent it we must direct attention not only to the condition of spasmophilia, but also to the management of the children who are always excitable and emotional.  In these children every burst of crying, however produced, whether by a fall, by a fright, by the entrance of a stranger, or by a visit to a doctor, is apt to be ushered in by a long period of apnoea, due to spasm of the glottis and of the diaphragm.  The first few expirations are not followed by any inspiration.  For several seconds the silence may be complete, while the child steadily becomes more and more cyanosed, or the body may be shaken by incomplete expiratory movements and strangled cries which are suppressed because the chest is already in a position of almost complete expiration.  In the worst cases, when the apnoea lasts a very long time, there may be convulsive twitching of the muscles of the face, or the attack may even terminate in general convulsions.  Very