PARATHYROID GLANDS 625 



It has long been known that, when the thyroid gland is extirpated, 

 metabolism is slowed up and the excitability of the whole nervous system 

 is diminished ; and this change in the general and especially in the nerve 

 metabolism may help to explain why the hyperexcitability of the nerves 

 that follows parathyroidectomy alone is lessened by simultaneous removal 

 of the thyroid. Halsted (a) (1907) reported some experiments on dogs, 

 made by him in 1888, that might be valued in support of this view. 

 In these experiments, the two superior parathyroids of the dogs were 

 probably deprived of their circulation. After the operation, hypertrophy 

 of both thyroid lobes developed, and 'the animals exhibited the signs of 

 chronic tetany. Halsted suggests that possibly the chronic tetany ap- 

 peared because the hypertrophied thyroids were imperfectly equilibrated 

 by the two parathyroids," and that, if thyroid hypertrophy had not resulted 

 from the experiment, the two inferior parathyroids would have been more 

 than ample for the prevention of tetany. 



In addition to the experiments of Halsted, there are in the literature 

 reports by a number of other investigators of experiments that indicate 

 that parathyroidectomy is regularly followed by hypertrophy of the thy- 

 roid gland (Edmunds, Lusena, Vassale and Generali, Halpenny and 

 'Thompson). 



When, on the other hand, the thyroid gland is removed, hyper- 

 trophy of the parathyroid glands develops. This hypertrophy occurs in the 

 external parathyroid glands of the rabbit after extirpation of the thyroid 

 gland and the internal parathyroids (Gley, Halpenny and Thompson, 

 Biedl). Hypertrophy occurs in the internal parathyroids of the rabbit 

 after extirpation of the external parathyroids and of the accessory para- 

 thyroids in the thymus (Haberfeld and Schilder). And in young dogs, the 

 intact parathyroids left behind at thyroidectomy were found a year later by 

 Biedl to be twice as large as those of control animals of the same litter. 

 Eiidinger assumes that this hypertrophy of the parathyroids after thyroid- 

 ectomy is due to the loss of function of an antagonistic organ (the thyroid). 

 Normally, he maintains, the function of the one gland is controlled by 

 that of the other, whereas, when this normal control is removed, the organ 

 left behind becomes functionally overactive and later shows anatomical 

 hypertrophy. 



In support of the theory that the thyroid and the parathyroids are recip- 

 rocally antagonistic organs, Riidinger has adduced certain other observa- 

 tions, namely (1) the clinical reports according to which myxedema pa- 

 tients were made worse and a patient suffering from Graves' disease was 

 benefited by the administration of parathyroid gland substance (Moussu 

 and Charrin), (2) the favorable effects of the serum of Mobius (from 

 thyroidectomized animals) and of rodagen (made from the milk of 

 thyroidectomized goats) in Graves' disease (attributed by Walbaum and 

 by Riidinger to the accumulated parathyroid secretion that resulted from 



