62 INTERNAL SECRETION 



rise as the characteristic features of the condition ; but we are 

 not in a position to define either the exact anatomical seat of 

 tetany, nor indeed the nature of the tetanic changes. One thing 

 only can be affirmed with certainty, and that is, that the affection 

 of the muscles is not myopathic in origin. 



PHYSIOLOGY OF THE THYROID GLAND. 



EXPERIMENTAL EXTIRPATION. 



A certain amount of light is thrown upon the functional 

 significance of the thyroid gland by the results which follow its 

 extirpation. It will be clear from what has gone before that, 

 before the function of the parathyroid glands was understood, 

 experimental extirpation of the thyroid could be of value in the 

 case of those animals only in which removal of the thyroid did 

 not necessarily include removal of the parathyroids. Hence, the 

 only results of any value were those obtained exclusively with 

 the herbivoras. As a matter of fact, it is only the more recent 

 experiments, those in which the parathyroids have been purposely 

 spared, which can be regarded as a rational basis for the investi- 

 gation of the phenomena associated with the thyroid gland. This 

 applies more particularly to the investigation of the pathogenesis 

 of those symptoms which characterize the suppression of the 

 parathyroid, as well as of the thyroid, glands. 



The results of thyrotoxic serum in the thyroid disturbance 

 have been investigated by various authors (Gontscharnkoff, 

 Mankowsky, Yates, MacCallum, Portis, Demoor and van Lint, 

 Liithke, Slatineano), but with very partial success. Several of 

 these describe a condition resembling cachexia thyropriva, but 

 in the greater number of instances the symptoms are those of 

 acute tetania parathyropriva. Slatineano found that, in addition 

 to its haemolytic action, thyrotoxic serum exercises a specific and 

 very decided influence upon the thyroid. In small doses, it acts 

 as a stimulant and promotes the secretion of colloid; after larger 

 doses, the colloid diminishes and there is hypertrophy of the 

 epithelial cells of the follicles, followed by acute degeneration 

 of these cells and their rapid destruction. Portis found that 

 the exhibition of thyrotoxic serum was followed by degeneration, 

 not of the thyroid only, but of the liver, spleen and kidneys. 

 Marchetti's finding, that the blood of patients with thyroid 

 affections gives a precipitation with thyrotoxic serum from 

 rabbits, was not confirmed by Schutze. 



.Both the recognition of the symptoms of suppression and the 

 estimation of their pathological significance are influenced by 

 one very important factor. It must always be remembered that 

 accessory glands, distinct from the principal organ and situated 



