EFFECT OF THYROID FEEDIXC,. 



28l 



Thirty-two Brown Leghorn chicks hatched April 9 were divided 

 into two lots, each containing 8 males and 8 females. One lot 

 was fed desiccated thyroid, beginning April 14: 10 mgm. daily 

 for 5 days, then 15 mgm. daily. On May 22, 43 days after 

 hatching, the moult had proceeded as shown by the following 



table. 



TABLE II. 



The second rectrices recorded for the controls were just 

 appearing. Those recorded for the thyroid-fed chicks were an 

 inch or more longer. In chicks numbered 17, 20, 21 and 23 the 

 variation in the notation indicates that one pair of first rectrices 

 was "quilled" and continuous with the second; in number 26, 

 3 pairs were "quilled" and similarly continuous with the second. 



5- 



In certain respects the modifications in structure and moulting 

 that we have described recall defects of structure and moult 

 that have been associated with fault-barring through the work 

 of Strong (1902), Riddle (1907, 1908, 19080) and Whitman (1919)- 



Strong (1902) called attention to abnormal transverse bands 

 in both remiges and rectrices of a hybrid pigeon, referable 

 clearly to defective barbules. He also described and figured one 

 of the body coverts, for the most part downy and carrying a 



20 



