feebleness or deficiency, either congenital or acquired, is, unfortu nately, a far from uncommon defect in childhood. The subject is an im portant one to the physician, for although he may not be called upon to treat such cases, he is often consulted upon the chances of recovery, and every degree of feebleness of mind, but especially the milder forms of im becility and mere backwardness, may be brought under his notice.
plays a very important part in the production of mental deficiency in the child. Imbeciles, fortunately, do not often marry, but a tendency to neurotic disease, such as insanity, epilepsy, etc., in the parents has a powerful influence in inducing feebleness of mind in their -offspring. Dr. Langdon Down, from careful investigation in two thousand cases of idiocy, found that in no less than forty-five per cent. a well-marked neurosis existed in the families of one or both the parents.
The scrofulous diathesis has been said to favour the occurrence of idiocy ; and there is uo doubt that a large proportion of imbeciles are the subjects of scrofulous cachexia. Still, mental feebleness is not a necessary part of the diathetic disease ; indeed, children of very evident scrofulous constitution often display exceptional intelligence. The explanation may probably be that the scrofulous habit tends to foster the influence of a neurotic tendency, and that the latter will operate with greater force and certainty in cases where it is associated with malnutrition in any of its forms. So, also, consanguineous marriages, and intemperance on the part of the parents, are well-known agencies in giving increased energy to any hereditary neurosis or morbid taint. Therefore any instability of the nervous system which may exist in such persons is likely to develope into a new and more striking phase in their offspring.
The above influences are influences of a very general kind, and all children born of the same parents must be equally subject to them. Idiots are seldom "only" children ; indeed, statistics show that they are often born of more than ordinarily prolific parents whose other children exhibit no sign of intellectual deficiency. This being so, we must look for other
and more special causes for their mental failing.
These special causes may either operate during gestation, at the time of birth, or after the child is born.
It is a suggestive fact that out of the two thousand cases investigated by Dr. Langdon Down no less than twenty-four per cent. were primiparous children. The cause of this undue preponderance in the first-born is no doubt owing, as Dr. Down points out, not only to the exalted emotional state of the mother during her first pregnancy—a state in which all causes 'of disturbance would naturally operate with exceptional force, but to the tediousness of the first labour, which is apt to give rise to a condition of suspended animation in the infant. Dr. Down's statistics well illustrate the force of these influences. Twenty per cent. of the idiots were born with well-marked symptoms of suspended animation ; and of idiots born in this condition, and only resuscitated by assiduous labour, no less than forty per cent. were first-born children. Bearing upon the same matter is the fact of the preponderance of male over female idiots, for the larger head of the former would increase the difficulty of parturition, and conduce to the state of suspended animation which experience shows to be so hurtful to the cerebral functions.
Whether the mother be a primipara or not, powerful emotional shocks are injurious, and may act very unfavourably upon her offspring. In no less than thirty-two per cent. of Dr. Down's cases there was a well-founded history of mental shock. Again, excessive sickness, by impairing the mother's nutrition, is also calculated to exercise an unfavourable influence upon the intellectual development of her infant. Dr. Langdon Down found in ten per cent. of his cases a history of marked and persistent vomiting.