Although the physiological effects of thyroid feeding may not be definitely recognised and understood, there is overwhelming evidence to show that it produces marked psychical results, that it acts as a direct cerebral stimulant, and we have every reason to rely upon it as a valuable adjuvant to our treatment of idiocy; and it is not too much to say that the treatment of this infirmity, as well as of other mental defects, by thyroid extract or some other preparation of the thyroid gland, is one of the greatest triumphs of modern medicine; but much still remains to be learnt, as Professor Victor Horsley remarks, "So definite and pronounced is the cachexia thyroidectomica, that few subjects in the range of pathology offer a more fruitful and inviting field of research."[48] _Craniectomy._--The operation of Craniectomy (that is the cutting of strips of bone from the cranium) has been recommended and practised in cases of microcephalic idiocy, an operation suggested upon the theory of premature synostosis, or closure of the cranial sutures, thus causing an arrest in the development of the subjacent cerebral tissue. Although I could not omit a reference to this operation, it has not met with general acceptance, and one of the most recent writers on this subject, M. Bourneville, physician at Bicêtre, discourages it altogether; and from his examination of the skulls of a number of idiots, he affirms that "in the immense majority of cases, there was no premature synostosis, and that neither normal anatomy, pathological anatomy, or physiology, justified the operation of Craniectomy."[49] The late Sir George Humphry was of the same opinion, as, after an examination of 19 microcephalic skulls, he said, "There is nothing to suggest that the deficiency in the development of the skull was the leading feature in the deformity, or anything to give encouragement to the practice lately adopted in some instances of a removal of a part of the bony case, with the idea of affording more space and freedom for the growth of the brain."[50] At a recent meeting of the New York State Medical Society, Professor Dana read a paper on Craniectomy for Idiocy and Imbecility, and he gave the following result of 81 cases:--In 35, there was improvement; in 22, no improvement; and death ensued in 24 cases. The conclusion at which Professor Dana arrives is that "it is largely through its pedagogic influence that an improvement takes place, and that the operation is allied in its effect to a severe piece of castigation!" Dr. Dana freely admits that this view of craniectomy for idiocy and imbecility lends itself readily to humour, and it would seem that he intended to kill the operation by ridicule.[51]