THE EELATION OF THE DUCTLESS GLANDS 153 



results in the enlargement of the pituitary, and 

 vice versa. Both the pituitary and the thyroid 

 seem to stimulate the sexual glands in the same 

 direction. If either is removed, not only does the 

 animal fail to grow properly, not only is there an 

 arrested development of the mind and a tendency 

 towards adiposity, but the sexual organs remain 

 undeveloped. 



As showing the parallelism in action of the thy- 

 roid and the pituitary in certain instances, the in- 

 teresting experiment has been performed of feed- 

 ing thyroidectomized rats with "tethelin," the sub- 

 stance isolated by Kobertson from the anterior 

 lobe of the pituitary: a beneficial effect on the 

 growth of the animals was observed. Are we to 

 assume that under certain conditions tethelin can 

 take the place of the thyroid hormone? 



Thyroid (A) and pituitary. See under pitui- 

 tary. 



(B) and sexual glands. Kemoval of the thyroid 

 stops the growth of the sexual glands. Castra- 

 tion, however, does not seem to have much influ- 

 ence on the thyroid, though it has been stated that 

 hyperactivity of the latter, in the shape of exoph- 

 thalmic goiter, is not uncommon. 



(C) and thymus. Conflicting results. 



(D) and parathyroids. At one time the para- 

 thyroids were regarded as adjuncts of the thyroid; 

 now the view is quite firmly established that the 



