408 



W. W. SWINGLE 



TABLE 7 

 April 17 



controls averaged 23.5 mm.; the iodin fed, 16.5 mm. The latter 

 had well-developed hind limbs. Iodin was again administered 

 for eight days and the animals measured. Table 8 indicates 

 the differences between the two sets of larvae. 



The fore limbs of the iodin-fed larvae appeared shortly after- 

 wards. 8ix of these animals were reared to metamorphosis 

 before death occurred. One of the lot was the smallest frog the 

 writer has ever seen. The controls for this lot developed jior- 

 mally, but have not at the present writing undergone metamor- 

 phosis. The fore limbs have not yet appeared. 



In a previous paper the writer had found that when thyroid 

 extract is adminstered to frog larvae, the alimentary tract under- 

 goes a remarkable shortening process in a brief space of time. 



