112 
GENERAL SUMMARY OF ABOVE EXPERIMENTS AND CONCLUSIONS. 
The experiments described above show that when potassium iodide 
or iodoform is administered to dogs the thyroids of the latter contain 
a greatly increased percentage of iodine and also are much more 
active physiologically. This result occurred too quickly to admit of 
any explanation other than that the increased activity was due to 
the increased iodine content. It seems to us to show conclusively 
that thyroid rich in iodine is more active than thyroid poor in iodine 
simply on account of the iodine; in other words, that the iodine is 
the cause and not the result of the activity. 
