60 THE DISEASES OF THE THYROID GLAND 



mal fall from center to periphery (Fr. Kraus) which is explainable by the 

 abnormal laxity of the tonus in the peripheral vessels. Even the earlier 

 observers (Graves, Stokes, Hirsch, Trousseau, et al.) noticed this opposition 

 between the increased cardiac activity as evidenced on the part of the heart 

 and the vessels of the neck, and the relatively slight filling of the peripheral 

 vessels. To the slight tonus of the peripheral vessels testify also the often 

 observable reddening of the face, the ears, the tips of the fingers and the 

 nail matrices (A. Kocher). 



So much for the clinical observation. Experimental investigations on 

 the action of the thyroid gland secretion upon the cardiovascular apparatus 

 are very numerous, but an agreement among them has not as yet been ob- 

 tained. Oliver and Schdfer, Fenyvessy, Haskovec, and others found after 

 intravenous administration of juice of thyroid gland sinking of the blood- 

 pressure and slowing of the pulse. Other observers found no action, or 

 acceleration of the pulse-rate. The different species of animals behave 

 differently, v. Cyon found that on the cat iodothyrin acted tonus-increasing 

 on the vagus and the depressor, v. Cyon and Oswald found the same true of 

 iodthyroglobulin, while iodine-free thyroglobulin is inactive. The increase 

 of excitability of the depressor nerve was also found by Asher and Flack. 

 v. Furth and Schwarz consider the depressor action of the extract not specific 

 for the thyroid gland, but attribute it to the cholin contained in the extract. 

 The differences in the results are to be explained by the fact that on the in- 

 travenous administration of thyroid gland, substances that influence the 

 cardiovascular apparatus are also introduced that have nothing to do with 

 the thyroid. According to the investigations of Falta, Newburgh, and Nobel, 

 the feeding of thyroid gland produced in most cases an increase in the fall of 

 blood-pressure from center to periphery, such as one observes in Basedow's 

 disease. Tachycardia is present, the blood-pressure taken at the brachial 

 remains the same (blood-pressure measurement according to Rocci} and fall 

 of the blood-pressure in the periphery (blood-pressure measurement accord- 

 ing to Gartner}. 1 On the administration of large doses of thyroidin there 

 results a significant fall in the blood-pressure (Pilez). By the heightening of 

 the fall the velocity of the circulation is increased, which best corresponds to 

 the increased oxygen requirement. 



The tachycardia is a result of the irritation of the accelerator, and the 

 slight tonus of the peripheral vessels is a result of irritation of the vasodilator ; 

 the dilation of the thyroid-gland vessels is the result of the irritation of -the 

 depressor nerve, as irritation of the root of the depressor nerve calls forth 

 an increase on the blood-pressure in the thyroid (v. Cyon). Also Asher and 

 Flack found that the excitability of the depressor nerve is increased by the 

 internal secretion of the thyroid gland. The increase of the blood stream 



1 An exception to this is shown only by diabetics, who show an increase in blood-pressure (see 

 chapter on pancreas). 



