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THE AMERICA X .\\ 1 TUBA LEST [ Vol. L V 



are strictly specific in as much as neither of them can re- 

 place the fmiction of the missing one. To quoting the in- 

 hibition of metamorphosis and growth following hypoph- 

 ysectomy as proof in favor of this view one could ob- 

 ject that in this particular case the thyroid can not effect 

 metamorphosis and growth merely on account of its 

 atrophic condition. Smith (36), however, found, that in 

 certain cases of partial hypophysectomy the thyroid re- 

 mains completely unaffected and. yet no metamorphosis 

 takes place ; only if the remaining fragment of the epi- 

 thelial hypophysis grows large enough to come in contact 

 with the neural hypophysis, metamorphosis can be ef- 

 fected. For this reason Smith takes the view that the 

 function of the hypophvsis is indispensable in metamor- 

 phosis and that the secretion necessary for this purpose 

 can only be elaborated, if epithelial and neural hypoph- 

 ysis are in contact with each other. That neither the 

 anterior nor the posterior lobe of the hy|)()physis rontaiii^ 

 the substance necessary for metamorphosis and that this 

 substance can be produced only in the body itself, requir- 

 ing for its elaboration the contact between neural and 

 buccal hypophysis, seems much supported by the fact 

 that, although growth may be maintained up to a certain 

 size, by feeding anterior lobe to hypophysectomized 

 tadpoles, metamorphosis can not be effected in such tad- 

 poles by feeding either anterior or posterior lobe. As 

 to the possibility of replacing the function of the anterior 

 lobe substance by introducing into the organism thyroid 

 hormone or iodine, Allen (28) fed iodine to hypophysec- 

 tomized tadpoles and obtained some, but not all of the 

 changes induced by iodine in normal and thyroideetoni- 

 ized larvae and seemed to be tardily inclined to the view 

 that the lack of the hypophsis could be coinpciisalci! for 



