His disease consists in an enlargement of the thyroid gland, which, occurring as it does chiefly in certain specific localities, has been ascribed to some Miasma. Within recent times a hsema-tozoon has been found in the blood of goitrous patients (Grasset). The enlargement of the gland may be uniform, but in many cases it is un-symmetrical, as in Fig. 382.

The lesion in ordinary goitre is primarily an increase of the normal gland tissue. This has sometimes the characters of a simple Hypertrophy, the saccules being multiplied. In other cases the new-formed tissue is discontinuous, occurring in the form of isolable tumours in the midst of the gland. To this form the name Adenoma is given. In many cases hypertrophy and adenoma co-exist.

In both forms the tissue is liable to secondary changes. An almost constant condition is colloid degeneration. Some saccules nearly always contain colloid matter, and in many cases there are many saccules greatly enlarged and distended with this substance. When this is sufficient to give a character to the naked-eye appearances the term Colloid goitre is used. Some of the altered saccules may assume preponderating dimensions so that Cysts develop.

The affected gland not infrequently undergoes Fibrous induration; the capsule and the connective-tissue septa become thickened. In the midst of the fibrous tissue pieces of gland tissue which have Undergone necrosis may be visible. In such indurated glands calcification commonly ensues, especially in necrosed parts. A true ossification has also been observed.

Fig. 382. - Goitre. There is enlargement chiefly of the left lobe of the thyroid.

Goitre is usually a simple affection, but a few cases are on record in which secondary tumours developed, chiefly in the bones. In a case observed by the author there were several such tumours in the bones of the skull, which presented the typical structure of the thyroid gland. The figures in the text are all from this case. Fig. 382 represents the thyroid enlargement, and shows the macroscopic appearance of the goitre. Fig. 383 shows a tumour of the parietal bone which had eroded the bone. In Fig. 384 the microscopic structure of the tumour is given and the saccules of thyroid tissue lined with epithelium are shown.

Fig. 383. - Secondary tumour in skull from case of goitre. The dura mater is raised and has carried the tumour tissue with it. The bone is eroded, and in one place perforated.