THE EARLY DEVELOPMENT OF DESMOGNATHUS 

 FUSCA.i 



HARRIS HAWTHORNE WILDER. 



In a former number of the American Naturalist (March, 1899) 

 I presented what seem to have been the only published observa- 

 tions on the development of one of our commonest and most 

 generally distributed salamanders, Desmognathus fusca, 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 object of my former sketch 

 were laid in the laboratory terrarium on or about June i, 1898, 

 but as the first observations were made on them^June 11, at 

 which time they were in the form of well-formed embryos coiled 

 about enormous yolk-masses, the first eleven days of the devel- 

 opment 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 Desmognathus 

 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 1. 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 forming to that of 16 

 cells, as represented by the first five rows of Fig. i. Nine of 

 these were preserved at once in 5% formaline, and the remain- 

 der 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- 



