Among all the recent observations destined to direct attention to the possible relations of some of the ductless glands or organs with endocrine functions to the growth and development of individuals, few have presented more striking phenomena than those reported by Gudernatsch.1 His exceptional experiments indicated, briefly, that if thyroid is fed to young tadpoles, development in the sense of a rapid differentiation of the parts proceeds with extreme rapidity, so that apparently perfect frogs of minute size speedily result. This differentiation in a developing vertebrate organism may be so rapid that within eighteen days after hatching, a stage is reached which would ordinarily require many weeks for its attainment. Thymus, on the other hand, had the power to stimulate growth, while lacking that of exciting differentiation; so that thymus-fed tadpoles experience a rapid growth but fail to be brought to metamorphosis within the usual period.
RECENT EXPERIMENTS RELATING TO THE ENDOCRINE GLANDS AND DEVELOPMENT. JAMA. 1916;LXVI(8):576. doi:10.1001/jama.1916.02580340032018