Interaction of Thyroid with Other Organs 43 



amount of adrenalin in the blood is increased in hyperthyroidism. Thus, 

 Ott and Scott got increase of adrenalin in the blood after intravenous 

 injection of thyroid extract : they obtained, however, a similar result after 

 injection of other organ extracts. With regard to exophthalmic goitre, 

 Krause observed dilatation of the pupil of the excised frog's eye when placed 

 in blood-serum of patients affected by this disease, although blood-serum 

 of normal individuals does not give this reaction. Krause has further ob- 

 tained chemical evidence of the presence of excess of adrenalin in blood 

 after injection into animals of the juice of thyroid gland from cases of 

 exophthalmic goitre, and its presence has also been demonstrated in such 

 cases by physiological tests (Fraenkel with the uterus ; Trendelenburg and 

 Broking with the frog's blood-vessels). It may therefore be assumed that 

 the secretion of the thyroid in exophthalmic goitre acts as a direct stimulant 

 to the suprarenal capsules, causing them to yield adrenalin to the blood in 

 larger quantity; a result which is also obtained with thyroid feeding. 

 But the fact that some cases of exophthalmic goitre benefit by the 

 exhibition of adrenalin is difficult of explanation on this hypothesis, for 

 this treatment should cause an exacerbation of the symptoms. Moreover, 

 it must be borne in mind that most of the physiological tests which have 

 been used for adrenalin would also be given by pituitrine. 



Incidentally, it may be mentioned that F. Munk noticed a diminution of lipoids 

 in the cortex of the suprarenals in animals fed with thyroid gland. 



With the Pituitary Body. — As has been pointed out above, a very 

 striking effect is caused by removal or atrophy of the thyroid upon the 

 pituitary body: which not only undergoes general enlargement, but also 

 exhibits well-marked indications of increased secretion. These changes 

 will be described when the pituitary is dealt with. 



What part, if any, concomitant removal of parathyroids may take in 

 promoting the changes in the pituitary is not certainly known. Accord- 

 ing to Halpenny and Thompson, some of the alterations which have been 

 described in the pituitary occur if the parathyroids only are extirpated. 

 But other observers have failed to find any changes in the pituitary after 

 parathyroidectomy. 



With the Thymus Gland. — Reference has already been made to the 

 anatomical and developmental relationship between thymus and thyroid, 

 to the effect of thyroid feeding of a pregnant animal upon the growth 

 of the thymus of the foetus, and to the supposed effect of the thymus 

 in assisting to produce the symptoms oV exophthalmic goitre: indeed 

 its removal by operation has been recommended and even practised in 

 that affection. In view of these circumstances some authorities believe 

 that there exists a mutual relationship between the two organs, and that 

 they exercise — by their internal secretions — an excitatory influence upon 

 one another. In conformity with this it has been stated that increase or 

 diminution in size of the two organs frequently go hand in hand. But 



