\ 



THE EFFECT OF THYEOIDECTOMY UPON NITRO- 

 GENOUS METABOLISM. By J. Herbert Parsons, 

 B.S., B.Sc, F.E.C.S. Eng., hdc Sharjiey Research Scholar 

 and Assistant to the Profcsso7^ of Physiology, University 

 College, London. 



(From the Physiological Laboratory, University College, London.) 



History. 



The probability that there are profound changes in the meta- 

 bolism of thyroidectomised animals is indicated by the chemical 

 changes in the tissues in myxoedema, and by the extreme emacia- 

 tion which ushers in the fatal result in carnivora. 



Michaelsen (1) was the first to take up the matter experi- 

 mentally. He found the gas exchange considerably higher after 

 total extirpation in starving cats, not only in cases which undergo 

 marked convulsions, but also in a case which went on to recovery 

 and showed few symptoms. The 00^ is especially increased ; 

 the moisture, on the contrary, having more the type of simple 

 starvation. The intake of oxygen shows a general increase, but 



with great oscillations, and the respiratory quotient ( — ^j is 



increased in all cases. Michaelsen considers that the chano-e 

 is brought about through the vaso-motor system ; it is 

 therefore probably another example of toxic effects upon 'the 

 medulla. 



Lorrain Smith (2) investigated the gas exchange very care- 

 fully and exhaustively in cats and kittens, using Haldane's very 

 accurate methods. He found little difference in animals kept at 

 a constant temperature. When normal animals are exposed to 

 a cold atmosphere, the production of CO, becomes increased, 

 consistently with the increased oxidation necessary to retain the 

 body temperature normal. This increase of CO., only occurs 



