THE RELATION OF THE PITUITARY AND THYROID 

 GLANDS OF BUFO AND RANA TO IODINE AND 



METAMORPHOSIS. 1 



BENNET M. ALLEN. 

 UNIVERSITY OF KANSAS. 



In the spring of 1918, Mr. Swingle and Mr. Etzen, working 

 in our laboratory, discovered the fact that iodine administered 

 in loose combination with flour brings about precocious meta- 

 morphosis in tadpoles after the same manner as the feeding of 

 thyroid gland preparations previously demonstrated by Guder- 

 natsch, '12. It at once occurred to the writer that iodine ad- 

 ministration would afford a means of testing out the role of these 

 two glands in metamorphosis. My plan was to administer 

 iodine in this manner to tadpoles deprived of their thyroid 

 glands, to those deprived of the pituitary gland and to those 

 deprived of both. Since the thyroid gland has always been so 

 completely identified with iodine in the animal body, the writer 

 suggested that Mr. Swingle make it a part of his problem to 

 feed iodine to thyroidless tadpoles. This he did with the result 

 that he demonstrated the fact that the administration of iodine 

 by feeding produces metamorphosis just as truly in thyroidless 

 tadpoles as in normal tadpoles. It was shown by the work of 

 Adler, '14, Smith, '16, and Allen, '16, that the removal of the 

 pituitary gland of tadpoles has a marked effect upon the thyroid 

 gland in that the colloid of the latter is of looser texture and 

 smaller amount than normal. Associated with this is the fact 

 that pituitaryless tadpoles do not undergo metamorphosis. 

 A pituitaryless tadpole of Rana pipiens has been kept by the 

 writer for two years without undergoing metamorphosis although 

 it has now grown beyond the size normally attained by tadpoles 

 of this species. These facts have led the writer to form the 

 hypothesis that the pituitary gland may play an active role in 

 metamorphosis, and that the thyroid gland would play the part 

 of a storage organ. This view was expressed in an earlier paper 



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