42 INTERNAL SECRETION 



zation of the parathyroid glands. The same method produced 

 paralysis in tortoises, ending in death. 



It would appear from the foregoing that the extirpation or 

 destruction of the parathyroid glands in all those species of 

 animals which have come under observation, gives rise to a 

 pathological condition, characterized by peculiar symptoms of 

 nervous derangement, and which, sooner or later, ends in death. 



My attempts to destroy the parathyroid glands of cats by 

 means of X-rays or radium emanations were, in all cases, un- 

 successful. 



According to Gontscharnkow, Mankowsky, Demoor, and van 

 Lint, the injection of thyrotoxic sera is followed by nervous 

 symptoms and by tetanic muscular convulsions. MacCallum tried 

 to obtain a cytolytic serum by immunizing geese with parathyroid 

 gland obtained from dogs. His careful experiments with dogs 

 show that the repeated injection of this serum was not followed 

 by clinical appearances, suppression of function, or by any 

 pathologico-histological change whatsoever in the activity of the 

 parathyroid glands. 



Partial parathyroidectomy, two of the glands being left intact, 

 is constantly performed in removing the thyroid from rabbits, 

 goats and sheep ; it is not usually followed by nervous symptoms. 

 In these cases, the remaining glands are uninjured, but with the 

 carnivore it is different. Here the partial removal of the para- 

 thyroids is attended either by unavoidable lesion of the remaining 

 glands, or by a disturbance of their blood supply. These cases 

 nearly always show more or less severe symptoms of tetany, 

 which, however, disappear spontaneously. 1 observed this 

 transient condition in dogs, in a fox, and in an ape where, in 

 removing the thyroid, the enucleation of the parathyroids was 

 attended with difficulty and these organs became unavoidably 

 crushed. The animals recovered after a short time. 



Tetany almost invariably follows the extirpation of more than 

 two parathyroids, but here also, if one parathyroid is left, the 

 effect is frequently only transitory. Should death, however, 

 result, it will be found that the remaining gland is atrophied or, 

 what is more frequent, that it is destroyed by secondary processes. 



If, after partial parathyroidectomy (removal of two to three 

 glands) no symptoms appear, the animal is then in the condition 

 known as "latent" tetany. Vassale observed this condition for 

 the first time in a bitch from which three parathyroid glands 

 had been removed. She developed a passing tetany, but com- 

 pletely recovered and had two puppies, which were, however, not 

 carried to term. She littered a second time, eighteen months 

 after operation ; she had four puppies and there was a profuse 

 secretion of milk. She was attacked quite suddenly by violent 

 tetany, but recovered after treatment with thyroid extract. 



The occurrence of tetany after partial parathyroidectomy in 



