RELATION OF lODIN TO THYROID 



407 



TABLE 6 



April 11 



several cultures containing fifty larvae each, only thirty animals 

 remained alive on this date. The controls had increased in size 

 during this interval, but none showed signs of limb development. 

 A new series of cultures of iodin-fed animals was started. The 

 animals averaged 13 mm. in length when first fed iodin. Eight 

 days later the first indications of body change appeared, and ten 

 days from the date of first feeding the limb buds of the experi- 

 mental larvae averaged 0.8 mm. in length. The controls showed 

 no 'signs of limb development. At this time the animals were 

 taken off the iodin diet and fed algae in order to prolong the ex- 

 periment, as the mortality rate was abnormally high. The con- 

 trol animals at this time averaged 19 mm. in length; the iodin-fed 

 larvae, 14.5 mm. For several days both sets of tadpoles were 

 fed only algae and then measured at the end of the period. The 



