17 
we are concerned, viz, the use of thyroid as a drug. It is not the 
condition of the thyroid in a living animal which is of interest in this 
connection. There may be and probably are delicate mechanisms by 
which the amount and strength of the secretion given off by the thyroid 
is accurately adjusted to the needs of the body. A gland may be 
supposed to form a large amount of very active material, but this 
may not reach the circulation owing to some abnormalities in the blood 
or lymph vessels or possibly to the absence of some stimulus which 
normally causes the secretion of the material. In the body the 
thyroid which has undergone cystic degeneration may be very 
ineffective in preserving health; but removed from the body and 
administered as a drug it may have pronounced effects. Similarly 
we may suppose that in some cases of Grave’s disease the thyroid 
contains normal amounts of active material but that the conditions 
for the rapid secretion or for the reabsorption of the iodine are so 
favorable, or that the capacity of the organism to destroy the secre- 
tion is lowered, so that there is an accumulation of the active ma- 
terial in the body outside of the thyroid. In such a case there might 
be a condition of hyperthyroidism, but the gland when administered 
to an animal as a drug might not be very active. In other words, 
the effects of a dead organ when administered as a drug can not be 
compared with the activities of the living organ in the body. Many 
of the writers who have discussed the relation of iodine to the thyroid 
have confused these two distinct problems. 
If we now turn to the experiments in which the question of the 
relation of iodine to the thyroid when used as a drug has been ap- 
proached directly, we find that there is no difference of opinion: all 
who have worked upon the problem from this standpoint agree as to 
the importance of the iodine. Unfortunately, however, the experi- 
ments of this character are very few and the results are not quantita- 
tive. 
The experiments bearing on this phase of the subject may be 
divided into three groups — ( a ) those in which the action of the thy- 
roid upon metabolism, ( b ) upon different forms of goiter, and (c) upon 
the circulation was investigated. 
The most important work upon the relation between the iodine 
content of the thyroid and its effects upon metabolism- was done by 
Roos, a who recorded the results of three such experiments upon a 
dog. In the first experiment the administration of 5 grams of desic- 
cated children’s thyroid containing 0.025 per cent iodine had almost 
no effect upon the excretion of nitrogen or upon body weight; later 
the administration of 5 grams of children’s thyroid containing 0.18 
per cent iodine caused an increase in the excretion of nitrogen of 
about 10 per cent. In the second experiment also a greater effect 
a E. Roos, Ztschr. f. physiol. Chem., 1899, 28, p. 40. 
61494— Bull. 47—09 2 
