Centrifugal Force upon Beetles^ E,ggs 



539 



these which were fixed immediately showed no effect of centrifugal 

 force; the other three hatched in six days. 



2 Experiments luith Leptinotarsa decemlineata 

 Series L.D. / 



At 3:30 p.m. on July 17 a female L. decemlineata was centri- 

 fuged for one hour with her posterior end toward the center. 



24. 



Fig. 24 Surface view of egg C.B. 12 laid by a centrifuged beetle, ap. = appendage. e.t.= em- 

 bryonic tissue, p. = posterior, j. = space between two yolk masses, y. = yolk. 



One egg was laid an hour after being centrifuged and others were 

 laid at irregular intervals until 9:30 the next morning, when the 

 total number reached seventy. The first egg laid, as well as all of 

 the others in the series, showed a stratification produced by centri- 

 fugal force. Only two layers, however, resulted, no gray cap being 

 discovered in the sections. The vesicular zone is not as large as 

 in older eggs centrifuged outside of the body of the mother for a 



