410 



W. W. SWINGLE 



TABLE 9 



animals and the mortality rate is very high when this compound 

 is fed for any length of time. Several cultures were kept long 

 enough to show the accelerating effect of this substance upon 

 metamorphosis. One culture, the animals of which averaged 

 12.5 mm. when first fed the iodoform, was kept for ten days. 

 During this interval the animals ceased to grow and showed the 

 reaction characteristic of iodin or thyroid feeding. Limb buds 

 were found on all of the experimental animals, but none on 

 the controls. This phase of the work was not carried out in 

 detail because of the toxicity of the iodoform mixture. . 



Discussion of the experiments with feedi7ig iodin to normal 

 larvae. The results obtained by feeding iodin crystals and 

 iodofonn are identical with those obtained when extract of the 

 thyroid gland is used as food. The changes typical of hyper- 



