THYROID AND ADRENAL GLANDS 33 



It has long been known that the removal of the whole thyroid 

 gland, including the parathyroid, occasioned marked interfer- 

 ence with nutrition and other changes, the chief of which are 

 disturbances of muscular coordination, possibly convulsions, 

 emaciation, apathy, and subsequent death. There is no duct 

 connected with the gland, and the secretion is therefore an in- 

 ternal one. Very little is known of it except that it is necessary 

 to the maintenance of life. If a very little of the gland be left, 

 or if, after its complete removal, a small bit of it be transplanted 

 in some other part of the body, or if the animal be fed on the 

 thyroid extract or the fresh gland, the characteristic symptoms 

 do not ensue. 



The muscular disturbances direct the attention to the central 

 nervous system when an attempt is made to explain the occur- 

 rences and it is not improbable that the effect of the thyroid 

 secretion is in some way exerted upon or through the central 

 system. It seems generally agreed that the thyroid does dis- 

 charge a secretion into the blood and that it is the withdrawal 

 of some part of that secretion from the circulation which is re- 

 sponsible for the remarkable train of symptoms sequent upon its 

 removal. This essential constituent is regarded by some as 

 being an agent which destroys certain toxic principles in the 

 blood, by others as being requisite to the metabolic functions in 

 the body without destroying anything. Baumann has isolated 

 from the gland substance a material containing a large propor- 

 tion of iodine, to which he gives the name iodothyrin, and it is 

 very probable that this is one, at least of the beneficial substances 

 in the thyroid secretion. 



Adrenal Glands. 



The adrenal gland or suprarenal capsules, rest ng upon the 

 upper ends of the kidneys, are ductless glands whose removal is 

 followed by weakness, impaired nutrition and disturbances in the 

 circulation. Death usually supervenes in two to four days. 



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