RELATION BETWEEN METAMORPHOSIS AND OTHER 

 DEVELOPMENTAL PHENOMENA IN AMPHIBIANS. 



By EDUARD UHLENHUTH. 



{From the Lahoratories of The Rockefeller Institute for Medical Research.) 

 (Received for publication, March 28, 1919.) 



In 1833 von Schreibers^ reported that in cold springs the larvae of salamanders 

 sometimes refrain from metamorphosis for a considerable length of time; upon 

 dissecting such larvae he found the remarkable fact that the sex organs had reached 

 maturity before metamorphosis had taken place. Since that time, similar ob- 

 servations have been made repeatedly; but it was due especially to De Filippi's^ 

 discoveries, communicated in 1861, that the attention of biologists was directed 

 to this phenomenon. De Filippi found a pond in the Formazza valley, near 

 Andermatten, which was inhabited by numerous individuals of the species Trilon 

 alpcstris. The majority of them had metamorphosed; but about forty were still 

 in a larval condition and possessed gills. They were conspicuous not only by 

 their unusually large size as compared with normal larva; of this species, but 

 also by the presence of mature sex organs. Soon after De Filippi's communica- 

 tion, DumeriP reported his remarkable experiments on amphibians — probably 

 the Mexican axolotl — in which it was demonstrated that the specimens in ques- 

 tion were larvae of the species Amhystoma tigriimm and not adult animals, and 

 yet the larvae not only possessed mature sex organs, but actually propagated 

 in the laboratory while still in the larval condition. 



These observations proved conclusively that the development of the sex or- 

 gans in amphibians is independent of metamorphosis. Expressed in terms of 

 Gudernatsch's^ discoveries, according to which metamorphosis is caused by the 

 action of definite substances, this would mean that the substances bringing about 

 development of the sex organs are not identical with the substances causing 

 metamorphosis. Recently the same condition has been found to prevail among 



^ von Schreibers, Oken's Isis, 1833, 527. 



2 De Filippi, F., Arch, per Zool. VAnat. e Flsiol., Geneva, 1861, i, 219 (quoted 

 by Wolterstorff). 



^ Dumeril, A., Nouvclles Arch. Miis. Histoire Nat. Paris, 1866, ii, 265; Ann. 

 sc. nat. Zool., 1867, vii, 229. 



^ Gudernatsch, J. F., Arch. Entwcklngsmcchn. Organ., 1912-13, xxxv, 457. 



525 



