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On comparing these different specimens it is evident that the thyroid gland in exophthalmic goître differs greatly from the normal gland, and still more widely from the cirrhotic gland in myxœdema. On the other hand it has a strong resemblance to the portion of gland which has undergone compensatory hypertrophy and which is in a condition of over-activity. The microscopical appearances thus indicate that bulk for bulk the thyroid gland in exophthalmic goître is in a state of much greater activity than in health, and when we consider that in the great majority of cases the whole gland is considerably enlarged, it is evident that the total amount of secretion formed and absorbed may be many times greater than in health.
Fig. 3.—Compensatory hypertrophy of thyroid gland of monkey. Zeiss obj. D., Oc. 2, camera lucida.
We know very little about the nature of the secretion of the thyroid gland in exophthalmic goître. It is probable that it is altered in quality as well as in quantity, but this is a question which must be left for future investigation to decide. All I wish to show is that we have a satisfactory anatomical basis for the view that the symptoms of the disease are due to an over-activity of the gland. Just as the structural changes in the thyroid gland in exophthalmic goître differ as widely from the normal in one direction as those found in myxœdema do in the other, so also we find that the symptoms of the two diseases offer a striking contrast, as has
