The most conspicuous example of benefit from the use of an organic substance is that afforded by the thyroid body. Schiff was the first to demonstrate that certain functional derangements and impaired nutrition accompanied by characteristic symptomatology followed removal of the thyroid body. A corresponding state was next observed in man by Reverdin, of Geneva, as a result of the surgical removal of the gland. Kocher, of Berne, next reported a series of cases similar to those of Reverdin, in which the total extirpation of the thyroid caused symptoms very similar to those described by Sir William Gull, and subsequently by Dr. Qrd, under the designation of myxoedema. The effects observed after removal of the thyroid consist in an affection of the skin and subcutaneous tissue and the mucosa; by changes in the cerebro-spinal functions, and by a remarkable cachectic state. By Kocher this complex of symptoms was called strumapriva cachexia. Schiff next demonstrated (1884) the important fact that this pathological condition might be removed and the status in quo restored by implantation of a fresh thyroid in the peritoneal cavity. Horsley was the first to suggest to substitute the thyroid of the sheep for relief of myxoedema by the process of grafting. Murray then proposed to effect the same result by injecting an extract of the thyroid prepared with the proper antiseptic precautions. Successful cases were soon reported by Fenwick, Beatty, Whipham, Corkhill, and others, of England; by Mendel, Wichmann, and others, of Germany; by Robin, Chopinet Chantemesse, and others, of France. The next most important step was the use of the gland itself, proposed by Dr. Howitz, professor in Copenhagen. At first this process consisted in feeding the raw gland in various forms to the subjects of myxoedema, but at the present time liquid extracts, the gland in powder, or compressed into tabloids, are employed, and with much success.

Various disturbances have ensued when too large quantity of the thyroid has been given. It is rare, however, that the actions are such as to compel its entire withdrawal. Among the symptoms caused by too free administration of the gland are the following: Headache, dizziness, numbness and tingling of the extremities, insomnia, a sense of fatigue, loss of appetite, wasting, urticaria, erythema and itching of the skin, rapid action of the heart, and sudden feebleness. By simply suspending its use for the time being, or by giving a diminished quantity, the ill effects will disappear.

As regards the quantity of thyroid to be given, the dose varies according to age and susceptibility. From one half to one gland a day, equivalent to a half to a teaspoonful of the extract, or one to three tabloids made of the desiccated substance three times a day, will procure the desired therapeutical effects.

The malady for which the thyroid is administered with entire success is myxoedema. The morbid complex constituting this peculiar disease is gradually removed, and, so long as the gland is made use of, does not reappear. It is now known, however, that occasional administration of the remedy is necessary to maintain the health at the normal standard. The influence of the thyroid is essential, and if, in consequence of its atrophy, that influence is withdrawn, obviously it must be supplied from without. Sufficient time has not yet elapsed to determine how long and to what extent the supplementary gland must be employed.

Obesity is another malady in which the thyroid has been used with success. It is almost the only remedy for this condition acting in a direct manner. It has the power to reduce the body-weight without any modification of diet or change in the manner of living. It must be given with caution, that the loss of flesh may not proceed too rapidly, and that cardiac depression may be avoided.

In exophthalmic goitre excellent results have been obtained by the use of the thyroid. The author has seen great improvement in cases of extreme difficulty. Some instances of goitre have been apparently cured, as reported by Ingalls and Metzgar, in this country.

Iodothyrine is an extract from the thyroid, rich in iodine, and is claimed to be an active principle, which is permanent in form and composition. Besides its utility in affections of the thyroid it has been successfully employed in the treatment of psoriasis and eczema. That it will take the place of the thyroid gland is more than doubtful. Indeed, to give iodothyrine most efficiently, it were better to feed the patient on the fresh gland itself. Undoubtedly, the best results have been had in this way. At the present time the thyroid tablet should represent the gland in its purity.