The Early Development of Desmognathus Fusca

IN a former number of the Anzcrib7an 1A72 Uu;L{ZI-alist (March, i899) I presented what seem to have been the only published observations on the development of one of' our commonest and most generally distributed salamanders, Desmoonat/i1us flsca, but as I was then unable to describe the early stages, a most essential gap in this history remained unfilled. The eggs which furnished the obj ect of my former sketch were laid in the laboratory terrarium on or about June I, i898, but as the first observations were made on them June i i, at which time they were in the form of xvell-formed embryos coiled about enormous yolk-masses, the first eleven days of the development remained unknown, a period which includes the extremely important cleavage stages, the formation of the blastopore and the beginning of the head and tail folds. Since that time a number of specimens of Desmi-oo-nathus have been kept in our terrarium each spring, and the favorite hiding-places investigated daily during the egg-laying season, but with no success until the present year (1903) when on June 22 at I.00 P. M., there was found a batch of twenty freshly laid eggs associated with a small but evidently mature female. At this time the eggs were in the early cleavage stages, and varied from the two-celled stage with the second cleavage form-ning to that of i6 cells, as represented by the first five rows of Fig. i. Nine of these were preserved at once in 5 % formalinie, and the remainder were killed, one or two at a time at intervals representing the most important stages. The eggs were, however, rather few in number, and in spite of considerable conservatism in the daily sacrifice, there were but two left when cleavage was com-