AUTHORS ABSTRACT OF THIS PAPER [SSI ED BY 

 THE BIBLIOGRAPHIC SERVICE, NOVEMBER 24 



EFFECTS OF THE EXTIRPATION OF THE THYROID 

 GLAND UPON OSSIFICATION IN RANA PIPIENS 



GEORGE S. TERRY 

 Department of Zoology, University of Kansas 



TWO TEXT FIGURES AND THREE PLATES 



INTRODUCTION 



The problem which is here described was undertaken at the 

 suggestion of Prof. Bennet M. Allen, to whom I wish first of 

 all to acknowledge my indebtedness for the incentive to this 

 work and for much kindly assistance. I shall merely endeavor 

 to discuss the effect of the extirpation of the gland upon the 

 growth and development of the skeletal system, in the hope 

 that this may be of some assistance to future workers who are 

 interested in the effects of the removal of the glands of internal 

 secretions. 



LITERATURE 



It has been shown in a number of papers that have appeared 

 during the last few years, that the removal of the thyroid gland 

 in rabbits, pigs, cats, dogs and even man produces a marked 

 retardation in the development of the skeletal system. 



Hofmeister ('92) found that the extirpation of the thyroid 

 of young rabbits, the external parathyroids being left 'in situ' 

 was followed by a retardation of growth and the development 

 of a condition of chronic cachexia. Further experiments show 

 that the arrest of growth was due to a remarkable retardation 

 of the process of ossification, both of the epiphyses and of the 

 synchondroses. The long bones, the pelvis and the vertebral 

 column, showed the greatest departure from the normal, the 

 skull the least. The growth of the long bones was retarded to 

 the extent of at least a third of their proper length, and micro- 



567 



