35 A. FRANKLIN SHULL. 



those which failed to hatch otherwise) did not show any increase 

 in the proportion of viable eggs. Indeed, drying had just the 

 opposite effect on inbred eggs. Even when the eggs were kept 

 dry only a few hours, the percentage of them that hatched was 

 reduced; and the longer the eggs were kept dried the fewer of 

 them hatched. Those that remained dry for four weeks did not 

 hatch at all. 



Other lines were not as sensitive to drying, for out of one lot of 

 eggs that were dry for nine months, several eggs hatched when 

 remoistened. 



In view of the results of desiccation of inbred eggs, it is con- 

 ceivable that the hatching of cross-fertilized eggs after drying 

 was due merely to the hastening of the development of eggs 

 whose hatching would otherwise have been spread over a long 

 period. If we had for comparison only the experiments with 

 inbred eggs which were dried immediately after laying, and those 

 with cross-fertilized eggs that were dried after they had been 

 allowed abundant time in which to hatch and had not done so, 

 the conclusion just stated would seem not merely conceivable, 

 but probable. However, since inbred eggs were also dried after 

 their normal hatching period was past, and failed to hatch sub- 

 sequently, whereas cross-fertilized eggs thus treated did hatch, 

 I am inclined to believe that drying for a few hours actually 

 caused some cross-fertilized eggs to hatch which would not have 

 done so without drying. From the physiological viewpoint, 

 such a difference between inbred eggs and cross-fertilized eggs is 

 not at all improbable. 



BIBLIOGRAPHY. 

 Shull, A. F. 



'13 Inheritance in Hydatina senta. I. Viability of the resting egg and the 

 sex ratio. Jour. Exp. Zool., Vol. 15, no. i, July, pp. 49-89. 



'15 Inheritance in Hydatina sehta. II. Characters of females and their 

 parthenogenetic eggs. Jour. Exp. Zool., Vol. 18, no. i, January, pp. 145-186. 



