96 INTERNAL SECRETION 



enlargement of the thyroid is not, as a rule, very considerable, 

 and is generally readily distinguishable from other forms of goitre. 

 Histologically, the goitre of Graves's disease is defined as a 

 parenchymatose hypertrophy of the gland, with profuse vascu- 

 larization. In addition to the active new formation of tissue there 

 are retrogressive processes ; and side by side with young follicles, 

 formed by epithelial proliferation, old follicles are seen to be 

 breaking up by means of cell desquamation. In older goitres 

 there is also a marked increase of interstitial connective tissue. 

 The goitre of Graves's disease is differentiated from all other 

 goitres by the nature of its histological changes. But it must be 

 borne in mind that the signs of an increased secretory activity 

 are the same as in the colloid goitres. 



Erdheim regards certain young cell formations with fat 

 granules as characteristic of the goitre of Graves's disease; while 

 according to Lobenhoffer, the acidophile granules in the proto- 

 plasm, which must be regarded as the secretory product of the 

 epithelial cells of the thyroid, are increased in exactly the same 

 way in Graves's disease as in colloid goitre. 



Of the pathological anatomical findings in Graves's disease, 

 hypertrophy of the thymus is among the most frequent (Thor- 

 becke, v. Hansemann, Boit, Monkeberg, Gierke, Capelle, Rossle). 

 The enlargement of the thymus is a centra-indication for 

 thyroidectomy, for after operation such cases frequently get 

 worse, owing, it is believed, to thymogenic auto-intoxication 

 (Gierke). The thymus hypertrophy is said to arise from a 

 vicarious endeavour on the part of the thymus to make good the 

 deficiency in the amount of secretion elaborated by the hyper- 

 trophied thyroid (Rossle). But the persistence or enlargement of 

 the thymus may be explained by the fact that the victims of 

 Graves's disease are frequently of lymphatic constitution ; and 

 the presence of the thymus as well as the hypoplastic arrest of 

 development of the genitals, like the frequent swelling of the 

 lymph glands and the formation of lymphatic deposits in the 

 thyroid gland, may only be the signs of a status thymicolympha- 

 ticus. 



The heart shows all the clinical signs of hypertrophy; more 

 rarely, there is dilatation of the left ventricle with fatty degenera- 

 tion or brown pigmentation of the muscle fibres. According to 

 Askanazy, an interstitial lipomatosis of the voluntary muscles, 

 which develops variously with the severity and age of the case, 

 is a constant finding. 



The other organic changes, and particularly the pathological 

 changes in the central nervous system, are not constant. 



The origin of the exophthalmos, which is almost patho- 

 gnomonic of Graves's disease, has always been the most difficult 

 problem in connection with the disease. 



The exophthalmos consists in an enlargement of the palpebral 



