EFFECTS OF THE ADMINISTRATION OR THE WITHHOLDING OF IODIN-CONTAINING COMPOUNDS IN NORMAL, COLLOID OR ACTIVELY HYPERPLASTIC (PARENCHYMATOUS) THYROIDS OF DOGS

The observations and experiments here recorded have been made on dogs, and include three with normal, eight with colloid and seventeen with actively hyperplastic glands, as ascertained by the first specimen of thyroid removed.The plan followed has been to remove a control portion of the thyroid from each dog for histologic diagnosis and iodin determination, and at intervals to remove other portions for comparison.Our experiments may be divided into two groups: (1) those in which iodin was administered and (2) those in which no iodin was adminis- tered, except what was contained in a liberal diet of cooked meat, bread, sodium chlorid, milk and water.The food being the same in each group, no other remarks are necessary, except that dogs normally store some iodin from such a diet.These two groups have been tabulated, and in presenting Tables 1 and2 we have arranged the cases according to the anatomic groups represented, as ascertained by the histologie diagnosis of the first specimen of thyroid removed.Thus normal and colloid glands are placed first; then follow in order the several degrees of hyperplasia.We shall discuss the cases according to the groups represented.1. Normal Glands.\p=m-\Of the three subjects (A-123, A-26, A-27), only one (A-26) was given iodin directly.In this case the iodin was distinctly but not markedly increased in the remaining lobe.This lobe also increased in size, but remained normal in structure.The other two subjects (A-123 and A-27) showed hyperplasia of the remaining lobes.These three cases show that iodin does have a preventive effect on the