252 Experimental Zoology 
with the result. Some experiments that I have carried out 
disprove this suggestion also. The lungs of tadpoles about to 
transform were removed at the base. The animals underwent 
their normal metamorphosis, as when the lungs are present. Not 
only was the tail absorbed, but the gills also. If the operculum 
that covers the gills is removed so that the gills are exposed to 
the water, they become absorbed at the proper time. How far 
these changes are comparable with senescence remains to be 
shown. 
LITERATURE, CHAPTER XV 
DAVENPORT, C. B. The Role of Water in Growth. Proc. of the Boston 
Soc. of Natur. Hist. XXVIII. 1897. 
Experimental Morphology, I. 1897. II. 1899. 
FEHLING, H. Arch. f. Gynakologie, XI. 1877. 
Minor, C. S. Senescence and Rejuvenation. Jour. of Physiol. XII. 
189g1. ‘ 
Morcan, T. H. The Origin of Species through Selection contrasted with 
their Origin through the Appearance of Definite Variations. Pop. 
Sci. Monthly. 1905. 
Ports, R. Landwirth. Versuch-Stat. XXIII. 1870. 
WEISMANN, A. Duration of Life, 1881. (Essays upon Heredity.) 
