OBGANOTHEBAPY AND HORMONOTHEKAPY 107 



arations can very rarely, if ever, prevent the development of tetany or cure 

 it once it has developed. However, some of the observations recorded 

 would appear to show that when not too large an amount of parathyroid 

 tissue has been removed the administration (by various routes) of parathy- 

 roid can prevent the development or lessen the severity of the tetany so that 

 life is prolonged until the remaining glandular tissue is able to hyper- 

 trophy sufficiently to meet the necessities of the case, or until, in some 

 other manner, the organism accommodates itself to the parathyroid in- 

 sufficiency. These experimental studies have thus furnished a basis for 

 the hope that in human tetany also parathyroid administration could be 

 useful to a limited extent. 



That a much greater therapeutic effect is exerted by implantation of 

 parathyroid grafts was quickly demonstrated in the laboratory. While 

 Schiff (c), in 1884, by implantation of thyroid tissue (which must have 

 also contained parathyroid tissue), was able to prevent tetany in thyroidec- 

 t.omized dogs, it was not until later, when the parathyrogenous origin of 

 tetany had been recognized, that grafting of parathyroid tissue was at- 

 tempted as a possible method of preventing or curing experimental tetany. 

 Such experiments, conducted by a large number of different investigators, 

 promptly showed that successful grafts exerted an unmistakably beneficial 

 effect in parathyroidectomized animals, although the results obtained were 

 very variable and often somewhat disappointing. That the implanted 

 parathyroid tissue is actually responsible for the claimed therapeutic 

 effects was perhaps most definitely demonstrated by Leischner, who found 

 that in animals, in which tetany had been prevented or cured by implanta- 

 tion of the extirpated glands, removal of the grafts one or two months 

 later was followed by tetany. It has been the experience of almost all 

 observers that these grafts rarely if ever persist for more than a relatively 

 short period. 22 Halsted (a) (b) (c) believed that the grafts will "take" 

 only if there be a parathyroid insufficiency with the organism suffering 

 therefrom, but that they will not take if the parathyroid tissue remaining 

 and that implanted taken together are able to prevent any insufficiency. 

 The various laboratory investigations indicate clearly that, in experimen- 

 tally induced tetany, implantation of parathyroid tissue has a definite 

 therapeutic effect similar in kind to but much more powerful than that re- 

 sulting from the administration of preparations of the gland. It appears, 

 however, that even the successful implantation of one or several glands does 

 not act as a certain preventative of or cure for tetany unless a certain 

 amount of functioning parathyroid tissue has escaped removal. This indi- 

 cates that grafted parathyroid tissue is able to compensate only for a sub- 

 total insufficiency (and then only for a time), thus enabling the animal to 



23 Christian!, however, was able to demonstrate microscopically their persistence 

 for two years in rats and for five years in cats in which he had reimplanted para- 

 thyroid tissues in their original sites. 



