THE THYROID APPARATUS 97 



fissure, which may be due to contraction of the levator palpebrum 

 muscle, together with a protrusion of the eyeball, brought about 

 by contraction of Miiller's protrusor bulbi muscle, the existence 

 of which in man has been proved by Landstrb'm. The latter 

 muscle has a sympathetic innervation, while the levator palpebrse 

 muscles are innerved by the autonomous oculomotor nerve. The 

 irritation of the sympathetic at the neck causes a protrusion of 

 the eyeball, in the course of which the space between the lids 

 undergoes a certain amount of secondary mechanical enlarge- 

 ment. The exophthalmos is undoubtedly a symptom of the in- 

 creased irritability of the sympathetic nerve, and this view is 

 supported by the adrenalin mydriasis which O. Lowi saw in 

 persons with Graves's disease. The enlargement of the space 

 between the lids, which sometimes takes place independently of 

 the protrusion of the eyeball, and Grafe's symptom, which con- 

 sists in the absence of synergy between the movements of the 

 eyeball and of the upper lid, are both signs of irritation of the 

 autonomous system (Eppinger and Hess). 



Tachycardia is also a constant symptom in Graves's disease, 

 though, as Chvostek points out, of very varying clinical signifi- 

 cance. The results of experimental research point to the sym- 

 ptom as a sign of increased irritability of the sympathetic nerves. 

 An irritation of the nervus accelerans, which hastens the heart's 

 action and belongs to the sympathetic system, suggests itself in 

 this connection. Experimental systematic hyperthyroidization 

 almost invariably produces tachycardia, and there is ground for 

 the belief that the acceleration of the pulse due to the increased 

 activity of the sympathetic nerve, is an effect of the increased 

 amount of thyroid substances circulating in the blood. The 

 hypertrophy of the cardiac muscle is sufficiently explained by its 

 continued hyperf unction. 



Other signs of the increased activity of the sympathetic 

 system are to be found in the greater vasomotor excitability, 

 the increased secretion of the sweat glands, the tendency to a 

 heightened temperature, and the increased production of heat. 

 The increased amount of adrenalin in the blood points to the 

 same conclusion. Kraus and Friedenthal discovered that the 

 serum of persons with Graves's disease caused the pupil of an 

 enucleated frog's eye to dilate, and later A. Fraenkel, by exact 

 biological experiments with the uterus removed from the living 

 body (" iiberlebend "), found that the blood of persons with 

 Graves's disease contained a very much increased amount of 

 adrenalin. 



Eppinger and Hess brought together a variety of symptoms 

 which they believe to be signs of irritation of the autonomous 

 nervous system. In addition to the enlargoment of the palpebral 

 fissure and Grafe's symptom, they include derangement of the 

 respiratory rhythm and diarrhoea among the symptoms of an 



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