LOSS OF THE FUNCTION OF THE THYROID GLAND. 



155 



intense heat of the skin (which disappear after several days), difficulty in seizing and eating food, 

 keratoconjunctivitis, and frequently disturbance of the rhythm of respiration with dyspnoea and 

 spasms of the abdominal muscles (Schiff). The arterial blood contains about the same amount of 

 as venous blood. Certain parts of the peripheral nerves undergo a kind of degeneration similar 

 to that found after nerve-stretching. There is albuminuria and fall of the blood-pressure. Death 

 usually occurs between the third and fourth day, the animals being comatose (Wagner). Schiff 

 found that if one-half of the gland was excised at once, and the other half a month afterwards, 

 death did not occur ; but Wagner denies this, for he asserts that the remaining half hypertrophies, 

 and if it be excised, death occurs with the usual symptoms. In monkeys, five days after the 

 operation, there are symptoms of nervous disturbance. The animals have lost their appetite, there 

 are fibrillar contractions of the muscles of the face, hands, and feet, but the tremors disappear on 

 voluntary effort. The appetite returns and is increased, but notwithstanding, the animal grows 

 thin and pale ; while the tremors increase and affect all the muscles of the body. These tremors 

 are of central origin, because they disappear 011 dividing the nerve. Thus there is profound 

 alteration of the motor powers. Amongst the outward symptoms are pufhness of the eyelids, 

 swelling of the abdomen, increased hebetude, and dyspnoea, while afterwards there is a fall of 

 the temperature and imbecility ; the tremors disappear, there is a palor of the skin, and ulti- 

 mately after five to seven weeks the animals die comatose. Thus there is a slow onset of hebetude, 

 terminating in imbecility. Very remarkable changes occur in the blood. There is a steady fall 

 of the blood-pressure ; a diminution of the red blood-corpuscles, or rather profound anaemia ; 

 leucocythsemia, the colourless corpuscles being increased to the ratio of four to fourteen ; and 

 lastly mucin is present in the blood, although normally it is not so. The salivary glands are 

 hypertrophied, owing to the presence of mucin, which is found even in the parotid, although 

 this is normally a serous gland ( 141). The swelling of the abdomen is due to hypertrophy of 

 the great omentum. Mucin is found in the peritoneal fluid, and the spleen is also enlarged. 

 Thus these symptoms present many features in common with those of myxcedema as described 

 by Ord (v. Horsley).] 



[Stages. Horsley distinguishes three stages. In the first or neurotic stage, the animals 

 exhibit constant tremors, 8 per second, and young animals do not appear to survive this stage. 

 In the second or mucinoid stage, mucin is deposited in the tissues and blood ; this change, 

 however, is only seen to perfection in monkeys. If these animals be kept at a high artificial 

 temperature, their life is considerably prolonged. In the third, atrophic, or marasmic period, 

 the animals die of marasmus, while they lose their excess of mucin. Age seems to exert an 

 important influence in thyroidectomy ; young dogs survive but a short time, while old dogs 

 merely exhibit symptoms of indolence and incapacity ; and, as a matter of fact, the activity of 

 the gland seems to be most active when tissue-metabolism is most active.] 



[The following table, after Horsley, indicates the symptoms that follow loss of the function 

 of the thyroid gland. 



Functions. The functions of the thyroid gland are very obscure. Perhaps it may be an 

 apparatus for regulating the blood-supply to the head (?). It becomes enlarged in Basedow's 

 disease, in which there is great palpitation, as well as protrusion of the eyeball or exophthalmos, 

 which seem to depend upon a simultaneous stimulation of the accelerating nerve of the heart, 

 and the sympathetic fibres of the smooth muscles in the orbital cavity and the eyelids, as well 

 as of the inhibitory fibres of the vessels of the thyroid. In many localities it is common to find 

 swelling of the thyroid constituting goitre, which is sometimes, but far from invariably, associ- 

 ated with idiocy and cretinism. [Horsley finds that its removal is the essential cause of 

 myxcedema and cretinism. He regards it (1) as a blood-forming gland, so that it has a hsema- 

 poietic function, but Gibson finds no grounds for supporting this view. During the anaemia 

 resulting from its removal, the blood of the thyroid vein contains 7 per cent, more red blood- 

 corpuscles than the corresponding artery (Horsley). (2) It seems to regulate the formation of 

 mucin in the body. After its removal the normal metabolism is no longer maintained, and 

 there is a corresponding increasingly defective condition of nutrition. J 



