ON THE DUCTLESS GLANDS. 237 
The Ductless Glands.—Report of the Committee, consisting of 
Professor Sir EDWARD ScH.AFER (Chairman), Professor SWALE 
VINCENT (Secretary), Professor A. B. MAcattum, Dr. L. E. 
SHorE, and Mrs. W. H. THompson. (Drawn up by the 
Secretary.) 
Mr. A. T. Cameron has continued his investigations on the presence 
and function of iodine in different tissues. Examination of the thyroids 
of the elasmobranchs Scylliwm canicula and Raia clavata gave positive 
results, those for female Scyllium thyroids (116 per cent.) being 
higher than any previously reported.1| Examination of the thyroids of 
the dog-fish Acanthias vulgaris, of the frog, of the alligator, and of 
the pigeon gave positive results, the variations found being traceable 
to variations in diet. Comparison of the iodine content of thyroid and 
parathyroid tissue in the dog gave such marked differences as to 
warrant the assumption that the parathyroid is not concerned with the 
production of iodine compounds, and, therefore, as far as these are 
concerned, that there is a differentiation of function between the two 
glands. 
A wider investigation has shown, in comparison with data previously 
published by others, that iodine is an almost invariable constituent 
of all organisms, plant and animal, the amount depending on the diet 
and medium of the organism. With higher development there is greater 
specificity of the tissue concerned in storing iodine, until in the 
vertebrates no tissue except thyroid contains appreciable quantities. 
Thymus especially has been examined in a large number of species, 
with negative results. All normal thyroids contain iodine, the amount 
varying with the diet, and between the limits 0°01 and 1°1 per cent. 
(dry tissue). Other observers have shown previously that sponges and 
corals (besides many algze) contain quantities of iodine comparable with 
that in the thyroid. Three other types of tissue have been found in 
marine organisms which contain amounts of iodine over 0'1 per cent. 
(dry tissue) viz.: the horny tubes of Eunicid worms, the external 
cutaneous tissues of the ‘ foot’ of the horse-clam, and the test of a 
tunicate. Further work will be carried out to determine the type of 
iodine compound in these tissues, with a view to throwing further light 
upon the type of iodine compound in the thyroid. The above results 
are in course of publication. 
Mr. Cameron is also engaged in work on the effects of feeding iodine 
compounds (and thyroid) on the amount of iodine present in the thyroid 
gland, with a view to determine the rate of increase or diminution. 
These results are not yet ready for publication. 
The Secretary has been engaged upon various problems connected . 
with the ductless glands. The effects of varying conditions upon the 
histological structure of the thyroid and parathyroid have been investi- 
gated in a preliminary fashion, but the results are conflicting and 
difficult to interpret. The variations in structure in normal thyroids 
1 Biochem. J., 2, 466, 1913. 2 J. Biol. Chem., 16, 465, 1914. 
