THE THYROID GLAND. 



941 



the tissues are not consequent on alterations in the nervous system. 1 

 The most characteristic nervous symptoms are those which have been 

 already mentioned muscular tremors, passing gradually into clonic 

 spasms, and finally, into convulsive attacks (tetany) ; there is also apathy 

 and unsteadiness of gait, and, with the advance of time, the gradual 

 supervention of a cretinic condition, together with a lowering of the 

 body temperature and a diminution of cutaneous sensibility. The tremors 

 also gradually cease. Monkeys die in from five to seven weeks after the 

 operation. The tremors are of central origin ; they disappear on section 

 of the motor nerve (Schiff), but not on removal of the cortical brain 

 area concerned with the movements of the part (Horsley). They also 

 disappear when a voluntary effort is made, and on reflex irritation. In 

 monkeys there is extensor paralysis of the upper limb, and there may 

 occur attacks of functional hemiplegia. 2 The attacks are diminished by 

 administration of potassium bromide. 3 The number of red corpuscles 

 per c.inm. becomes mark- 

 edly diminished, while the 

 white corpuscles tend to 

 increase in number. The 

 salivary glands become 

 swollen and enlarged, and 

 contain an excess of 

 mucin. Changes in the 

 composition of the blood 

 have also been observed, 4 

 and in the proportions of 

 the blood gases, 5 and de- 

 generative changes have 

 been described in the 

 kidneys. 6 It has been 

 shown that the excita- 

 bility of the cortex of the 

 brain, and even of the 

 lower centres, is increased 

 in animals which have 

 suffered from thyroid- 

 ectomy, 7 but with the FlG > 84. Monkey deprived of thyroid. HORSLEY. 

 supervention of the cretinous condition it is diminished. 8 The metabolic 

 changes which occur are most obvious in the connective tissues, and 



1 Whitwell (Brit. Med. Journ., London, 1892, vol. i. p. 430) found what he regards as 

 pathological changes in the nerve-cells of the Rolandic area in a case of myxredema. Marked 

 changes in the nervous elements have also been described as a feature of the condition 

 of cachexia thyreopriva ; Kopp, Ttrchow's Archiv, 1892, Bd. cxxviii. S. 290; Langhans, 

 ibid., S. 318; Capobianeo, Internal. Monthly Journ. of Anat. and Physiol., 1894, Bd. xi. 

 S. 471 (abstract in CentralbL f. PhysioL, Leipzig u. Wien, 1893, Bd. vii. S. 112) ; Lorrain 

 Smith and Pembrey, " Proc. Physiol. Soc.," Journ. PhysioL, Cambridge and London, 

 1894, vol. xv.; Quervain, Vircliow's Archiv, 1893, Bd. cxxxiii. S. 481. Vassale and 

 Donaggio found degeneration in the pyramidal tract (!) of dogs, after extirpation of the 

 parathyroids (Arch. ital. de biol., Turin, 1896, tome xxvii. p. 129). 



2 Horsley, loc. cit. 



3 Gley, Compt. rend. Soc. de biol., Paris, 1892, p. 300. 



4 Halliburton, loc. cit. ; Ducceschi, CentralbL f. Physiol, Leipzig u. Wien, 1895, p. 

 359, and 1896, p. 217 ; also Arch. ital. de biol., Turin, tome xxvi. p. 209. 



5 Albertoni and Tizzoni, loc. cit. (see also p. 943). 



6 Rosenblatt, Arch. d. sc. biol., St. Pe"tersbourg, 1894, p. 53. 



7 Autokratoff (abstract in Brain, London, 1890, vol. xxiii. p. 424), 



8 Horsley, Brit. Med. Journ., London, 1892, vol. i. p. 267. 



