50 INTERNAL SECRETION 



that the beneficial results of thyroid administration are due to 

 the fact that parathyroid tissue is given at the same time ; experi- 

 ments by Pineles have, however, shown this view to be untenable. 

 He found that the amount of parathyroid substance contained 

 in the thyroid glands of sheep and calves is by weight i in 309 

 and 379 respectively; while 200 times that amount of parathyroid 

 substance, when added to thyroid tabloids, had no therapeutic 

 effect whatsoever. 



There are numerous accounts by reliable observers of the 

 favourable effects of thyroid gland and thyroid extracts in the 

 tetania parathyropriva of animals. 



Kocher, the greatest authority upon the parallel condition in 

 man, wrote in 1906, at a time, therefore, when the significance 

 of the parathyroids in post-operative tetany was well known to 

 him, as follows :- 



" We found that by energetically pushing the thyroid extract 

 and iodothyrin in large doses, we were able to procure a rapid 

 abatement of the symptoms of tetany and, by continuing the 

 treatment over long periods, we obtained a cessation of the 

 attacks." 



The favourable influence of the thyroid extracts in post- 

 operative tetany will not be questioned by those who have wit- 

 nessed the remarkable improvement which takes place, almost 

 immediately, after the subcutaneous injection of soluble thyroid 

 preparation, in the condition of animals with severe tetanic 

 symptoms ; or that which, after one to two hours, follows the 

 administration by the mouth of fresh or dried thyroid gland. 

 Nor will the efficacy of these substances be held in doubt by 

 anyone who has, by this means, kept animals alive for two to 

 three weeks after parathyroidectomy, while the animals not so 

 treated died of tetany in a very much shorter time. 



But these results must not be accepted without criticism. It 

 must always be taken into consideration that the clinical picture 

 produced by experimental tetany is in the highest degree variable ; 

 that spontaneous remissions and far-reaching improvements are 

 of as frequent occurrence as sudden relapses, and that in certain 

 cases this renders the prognosis extremely difficult. The sudden 

 termination of a tetanic seizure, the cessation of the muscular 

 tremors, and even the temporary disappearance of the nervous 

 hypersensibility, cannot always be taken as evidence in favour 

 of the treatment, for all this may, in rare cases, occur spon- 

 taneously. 



It is an important point in favour of thyroid extract that 

 improvement follows rapidly upon treatment, and that the life 

 of tetanic animals is very much prolonged by its use. Vassale 

 tries to explain the results of thyroid treatment in tetany by the 

 presence of supernumerary parathyroid glands, which are sup- 

 posed to exercise the same effect as the implanted glands or those 



