author's abstract op this paper issued 

 by the bibliographic service, december 23 



STUDIES ON THE RELATION OF lODIN TO THE 



THYROID 1 



II. COMPARISON OF THE THYROID GLANDS OF lODIN-FED 

 AND NORMAL FROG LARVAE 



W. W. SWINGLE 



Fellow in Biology, Princeton University 



INTRODUCTION 



In the foregoing paper (part I of these studies) the writer 

 described the effects of feecHng iodin and various of its com- 

 pounds to normal and thyroidless frog larvae. It was found 

 that the administration of iodin, iodoform, and potassium iodide 

 greatly accelerated metamorphosis in these animals, despite the 

 fact that normally thyroidless tadpoles never assume the adult 

 characters. 



The results obtained with feeding iodin to thyroidectomized 

 larvae had led the writer to advance the view that iodin functions 

 within the organism as a hormone itself, without the inter- 

 mediation of the gland. Furthermore, it was suggested that the 

 chief function of the thyroid appears to be that of iodin storage, 

 and not, as the current view would have us believe, the elabora- 

 tion of internal secretion. The present paper is a presentation 

 of the results of a comparative study of the thyroid glands of 

 iodin-fed and normal animals of the same age together with 

 some additional data gathered since the publication of part I of 

 this series on iodin feeding and amphibian metamorphosis. 



MATERIAL AND METHODS 



Some of the material used in the present work was obtained 

 from the iodin-fed and control cultures described in part I. The 



^ The experimental work for this paper was done while the writer was 

 instructor in zoology at the University of Kansas. 



417 



