PHYSIOLOGY IN THE STUDY OF DISEASE 97 



certain Italian physiologists first proved that it is 

 the removal of these and not of the thyroid which 

 is followed by the symptom of tetany. 



When in 1913 I was writing upon the various 

 structures which, like the thyroid, regulate the 

 chemical changes in the body, I was struck by our 

 ignorance of the functions of these parathyroids 

 and of the want of knowledge of how their removal 

 caused this peculiar condition. 



This set me to work to try to find out, and in this 

 investigation I was joined by Dr. Leonard Findlay 

 of the Eoyal Hospital for Sick Children, Glasgow, 

 and by various members of the Staff of my Labora- 

 tory. It gives me pleasure to acknowledge the 

 financial help given by the Medical Research Com- 

 mittee in the prosecution of these investigations. 



As the result of our experiments we were able to 

 show that, after removal of the parathyroids from 

 animals, some injurious or toxic substance develops 

 in the blood and causes the symptoms, and that 

 if the animal be bled and salt solution run into 

 the circulation the symptoms disappear for some 

 time, but recur. This observation had been previ- 

 ously made by Macallum. We found that the 

 spasm of the muscles is due to increased excita- 

 bility of the nerve-cells in the spinal cord from which 

 the nerves to the muscles take their origin, but that, 

 on the other hand, the increased response of the 

 nerves and muscles to mechanical or electrical 



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