632 INTERNAL SECRETION 



while at other times all or some of the parathyroid tissue would be 

 spared.) [Add to this that sporadic masses of thyroid tissue (acces- 

 sory thyroids), often existing as far down as the root of the aorta 

 (always, indeed, in certain animals e.g., the dogl, must necessarily 

 be spared in the most complete thyroidectomy, and it will cease to 

 excite surprise that the symptoms and pathological changes de- 

 scribed after that operation should have been so various and so 

 contradictory. J We know now that the parathyroids are perfectly 

 distinct organs from the thyroid in histological structure, in func- 

 tion, and in the consequences of their removal. The parathyroids, 

 for instance, contain no iodine, while iodine^ is a characteristic 

 constituent of the tfiyroid. Nor do the parathyroids show any 

 compensatory hypertrophy when the thyroid alone is excised, or 

 any changes which would indicate a definite relation to, still less an 

 active participation in, the pathological processes occurring in the 

 thyroid in goitre. I This does not mean, however, that there are 

 no points of contact between the functions of the two glands. The 

 more the matter is probed, the more clearly does it appear that none 

 of the organs is quite independent of the rest, and the reciprocal 

 relations of the ductless glands are probably of exceptional im- 

 portance. But the premature attempts which have been made, 

 in the absence of a sufficiency of exact data, to represent their 

 mutual influence by crude schemata, have retarded rather than 

 advanced our knowledge, and need not be referred to here. 

 ( Parathyroidectomy.yrTotal extirpation of the parathyroids is 

 followed by a train 01 acute symptoms, ending fatally, as a rule, in 

 from one to ten days. The typical nervous symptoms following the 

 operation have been described as those of ' tetanyf and the tetany 

 which used to be included among the consequences of removal of 

 the thyroid is now known to be due to the simultaneous excision 

 of the parathyroids (Kocher). A cat, after the combined operation, 

 is perfectly well on the first day. On the second day a curious 

 shaking of the paws is seen, tremors of central origin soon appear, 

 and increase in severity, until at length they culminate in general 

 spasmodic attacks. Even when the animal is at rest the fore-legs 

 tend to be flexed, while the hind-legs are extended, and this attitude 

 is exaggerated in the convulsions. In the later stages unconscious- 

 ness is associated with the onset of the convulsions. Similar results 

 follow excision of the parathyroids alone in dogs. J Although the 

 tetany is the most striking symptom, it is only one token of a pro- 

 found general disturbance of nutrition. The pulse-rate and the 

 rate of respiration are markedly increased. There is fever and pro- 

 fuse salivation, with dilatation of the stomach and duodenum, due 

 to the loss of muscular tonicity. In the intervals between attacks 

 the tonus returns to the normal. The secretion of the gastric 

 juice, pancreatic juice, and bile are interfered with (Carlson, etc.). 



