92 THE GLANDS REGULATING PERSONALITY 



the job of extirpating the thyroid while leaving the parathyroids 

 intact and vice versa. In consequence some definite information 

 about the parathyroids is available, even though their internal 

 secretion has never been isolated, or its existence established as 

 more than an inference. 



When the parathyroids are removed, an astounding increase 

 in the excitability of the nerves follow. It is as if the animal 

 were thoroughly poisoned with strychnine. The slightest stimu- 

 lus will make him jump, or throw him into a spasm. When the 

 excitability of the nerves is measured by an electrical instrument 

 it is found augmented by from five hundred to one thousand per 

 cent. The reflexes, those automatic responses of brain and spinal 

 cord to certain stimuli and situations, become enormously sensi- 

 tive, so that merely letting the light into a darkened room will 

 make the subject of the experiment go into a series of convul- 

 sions. 



On the chemical side, an explanation for these nervous phe- 

 nomena has been advanced. Lime in the blood and cells appears 

 to be necessary in a number of ways. In the making of bone 

 and teeth, in the coagulation of the blood, in the keeping of fluid 

 within the blood vessels, and in maintaining the tone of the 

 nerves, it plays a major role. Now the parathyroids, among all 

 the glands of internal secretion, seem to act as the prime regula- 

 tors of the amount of lime held within the blood and cells. For 

 when the parathyroids have been completely and aseptically ex- 

 cised, without injuring any other organ, immediately the body 

 begins to lose lime. Something has gone out of it that helped 

 it to bind lime, and without that essential something, the internal 

 secretion presumably of the parathyroids, the lime departs. As 

 a conspicuous consequence the teeth fail to develop properly, 

 particularly as to their enamel, for which lime is an essential 

 constituent. Hair is lost, there is a general wasting, the nails 

 get brittle, and the bones soften, and the animal dies. Supplying 

 lime directly, particularly by direct injection into the blood, will 

 relieve the symptoms. 



In man, a condition of nervous over-excitability has been 

 described as tetany. It occurs most often in the young, the preg- 

 nant, or in vomiting after operations. All sorts of tests have 

 related the malady to the phenomena succeeding parathyroic 

 deprivation, and they are now looked upon as aspects of it 

 Individuals havo been reported suffering from an insufficiency o: 

 the internal secretion of parathyroids, with a sudden extreme de- 



