

EGG-CLUSTERS OF UNFERTILIZED FEMALES. 367 



ing up of the eggs of the last brood was not due to their 

 parthenogenetic characteristics, but to outside influences, 

 and further states that it would be premature to limit the 

 vitality of the products of parthenogenesis to two genera- 

 tions. It is a matter of regret that Weijnbergh did not 

 examine the eggs each fall, and see whether the embryo 

 had formed ; for, had this been found, there would have 

 been greater reason to have supposed that the eggs had 

 dried up because of outside influences, as Dohrn conjectured. 

 Mr. W. J. Pearce of Bath, England, reports in " The Ento- 

 mologist," Vol. XII, page 229, that he had a female of this 

 moth, which had not mated, lay eggs which hatched the 

 following year. 



EGG-CLUSTERS or UNFERTILIZED FEMALES. 



The egg-clusters deposited by unfertilized females, in the 

 experiments on parthenogenesis, in 1893, were, as a rule, 

 irregular, scattering and poorly covered with hair. As 

 these were all laid in boxes, it was thought that it might be 

 due, in part at least, to the smoothness of the box, which 

 did not allow the moth as good a foothold for oviposition 

 as is afforded by the surfaces usually selected for the pur- 

 pose, such as the rough bark of trees, etc. The observa- 

 tions of the field inspectors led them to various conclusions, 

 some contending that unfertilized females never lay the 

 regular egg-clusters characteristic of the fertilized female, 

 while others were of the opposite opinion. Investigations 

 were made during the summer of 1895, to learn whether it 

 is possible to determine, from the form and completeness of 

 an egg-cluster, whether the eggs contained in it are fertile. 

 August 2, twenty-five recently emerged, unfertilized female 

 moths were placed in a cage, made by tacking cheese cloth 

 over a hoop, which projected from the trunk of a white oak 

 ( Quercus alba) . This species of tree was selected because 

 the bark is of such a nature as to give the moths the most 

 favorable opportunity for egg-laying. At the end of two 

 weeks, all the moths being dead, the cage was opened and 

 six very imperfectly formed egg-clusters were found. They 

 were, in fact, simply small patches of eggs, with but little 

 of the usual covering of hair. October 10, the eggs were 



