800 THE ENDOCRINE ORGANS, OR DUCTLESS GLANDS 



toms of this disease, a result of some condition elsewhere. In this con- 

 nection it is of interest to note that degenerative and pigmentary changes 

 in the ganglion cells of the cervical sympathetic have been found by Wil- 

 son 44 in cases of exophthalmic goiter and which are believed to be dis- 

 tinctive of this condition. On this account disease of the sympathetic 

 is suggested, by some, as the possible cause of the cardiac and ocular 

 symptoms, as well as of the thyroid hyperactivity, the latter producing 

 secondarily, it is supposed, the metabolic phenomena characteristic of 

 the disease. 



The Relationship of the Thyroid with Other Endocrine Organs 



1. With the Generative Organs. Evidence of an association between 

 the female generative organs and the thyroid is very strong; thus, the 

 thyroid becomes enlarged at puberty, during the menses, and during 

 pregnancy, and in thyroidectomized young animals the sexual glands 

 fail to develop properly. 



2. With the Adrenal Glands. (See page 788.) 



3. With the Pituitary Body. After removal of the thyroid, the pitu- 

 itary becomes greatly altered and enlarged, particularly the pars an- 

 terior, in which it is not uncommon to find that a certain amount of 

 vesicles containing colloid, not unlike those of the thyroid, become devel- 

 oped. This colloid material, however, does not contain iodine. It is said 

 that this increase of the pituitary after thyroidectomy does not occur if 

 thyroid extract be administered. Increased activity of the pars inter- 

 media of the pituitary is also quite plain. These facts would at first 

 sight seem to indicate that the pituitary and the thyroid can act vica- 

 riously, but this is very doubtful, for it has not been found that pitu- 

 itary extract has any beneficial effect in the treatment of goiter and myx- 

 edema. Nevertheless the association in function of the two glands must 

 be more or less close, not alone for the above reasons, but also because they 

 are both associated to much the same degree with the sexual organs, 

 and both act on the higher functions of the nervous system in much the 

 same manner. 



4. With the Thymus Gland. The persistence of the thymus in ex- 

 ophthalmic goiter, as well as the anatomical and embryological relationship 

 between thymus and thyroid, is taken to indicate some close relationship. 



THE PARATHYROIDS 



Experimental Parathyroidectomy 



Experimental parathyroidectomy yields results which vary in dif- 

 ferent groups of animals, undoubtedly because of the fact that in some, 

 such as the rat and rabbit, accessory parathyroids may exist. In gen- 



