RELATION OF lODIN TO THYROID 



419 



was fed very little in order to hold the growth of the animals 

 in check so as to keep them approximately of the same body 

 length as the animals of the iodin-fed culture. The length of 

 the well-fed group of controls only is indicated in the table; the 

 animals of the underfed culture measured 10.5 mm. 



TABLE 1 



Microscopic examination of the thyroid glands of this series 

 of tadpoles revealed a rather interesting condition; the glands of 

 the iodin-fed larvae were approximately of equal size with those 

 of the controls. This, despite the fact that in regard to body 

 size, the iodin-fed animals were only half the size of the controls 

 as a glance at table 1 shows. When the glands of the iodin-fed 

 animals were compared with those of normal animals of the same 

 age held at 10.5 mm. by underfeeding, it was found that the 

 iodin-fed larvae had considerably larger glands. The average 



