THE THYROID GLAND. 
94 1 
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 
Bupervention 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 (Setoff), 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.mm. 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. 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.— Hoksley. 
supervention of the cretinous condition it is diminished. 8 The metabolic 
changes which occur are most obvious in the connective tissues, and 
1 Vhitwell [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 myxcedema. Marked 
changes in the nervous elements have also been described as a feature of the condition 
of cachexia thyreopriva ; Kopp, Virehow's Archiv, 1S92, Bd. cxxviii. S. 290; Langhans, 
ibid., S. 318; Capobianoo, Interned. Monthly Jowrn. 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," Jour a. Physiol., Cambridge and London, 
1894, vol. xv.; Quervaiu, Virehow's Archiv, 1893, Bd. exxxiii. S. 481. Vassale and 
Donaggio found degeneration in the pyramidal tract (!) of dogs, after extirpation of the 
parathyroids {Arch. ital. de liol., Turin, 1896, tome xxvii. p. 129). 
2 Horsley, loc. cit. 
3 Gley, C'ompt. 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. Petersbourg, 1894, p. 53. 
7 Autokratotf (abstract in Brain, London, 1890, vol. xxiii. p. 424). 
8 Horsley, Brit. Med. Journ., London. 1892, vol. i. p. 267. 
