14 INEZ WHIPPLE WILDER. 



eggs, however, as may occur in making a transfer from out of 

 doors to the laboratory, the mother goes back to them again, 

 even though the nest and all of its surroundings may have been 

 reconstructed. I have never had the opportunity to further 

 test the sense of ownership of eggs in a mother by exchanging the 

 eggs of two individuals, but the experiment would certainly be 

 an interesting one." 



In connection with later experiments upon the mating habits 

 of Desmognathus fusca, certain facts have come under my 

 observation which give more definite information concerning this 

 brooding instinct of the mother and her behavior during the 

 brooding period. These facts furnish, in addition, more exact 

 data concerning the length of the incubation period of the species, 

 which, at the time of the publication of my account, was not 

 definitely known. 



On July 2, 1915, late in the afternoon, a female Desmognathus 

 fusca which had been under observation in the laboratory since 

 May 20, 1915, confined in a terrarium with another gravid 

 female and a male, was found to have deposited a batch of eggs. 

 These had been laid within the previous twenty-four hours, and 

 were in the early segmentation stages when found. The com- 

 panion male and female were immediately removed from the 

 terrarium and in order to make sure that the eggs were actually 

 those of the female with whom they had been found associated, 

 the companion female was examined and found to be still gravid. 



The terrarium in which the eggs were laid was a rectangular 

 glass one, measuring 13 inches long by 8 inches wide by 13 

 inches deep, and had a two-inch layer of wet sand in the bottom, 

 sloping down at one corner to allow the water to stand in a 

 shallow pool. Upon the sand had been placed wet sphagnum 

 moss, and a stone about 4 inches in diameter was lying upon the 

 sphagnum near the end of the terrarium which was opposite 

 to the pool. It was in a cavity in the sphagnum underneath 

 the stone that the eggs, 22 in number in two clusters, were found 

 with the mother coiled about them in the usual brooding position 

 of the species. 



During the subsequent weeks the stone was frequently lifted 

 to examine the nest, in the evening as well as during the 



