522 



R. W. Hegner 



tion. The hatching period of approximately six days is the nor- 

 mal one for eggs of this species. 



C.B. /f, h. This egg, which was centrifuged for thirty minutes, 

 also developed normally, the larva hatching in six days. 



C.B. ^, z, y and k. None of these eggs continued its develop- 

 ment farther than the early cleavage stages. 



TABLE III 

 CaUigrapha higshyana — Series C.B. 3 



When taken from the centrifugal machine at the 



Series C.B. 3 — Table III 



Series C.B. 3 will serve to show the effects of a centrifugal force 

 applied for four hours to fresh eggs with their anterior ends toward 

 the axis of rotation. 



C.B. J, a. The control egg was normal and in a stage slightly 

 younger than that shown in Fig. 9. 



C.B. 3, h 



end of four hours this egg appeared stratified in a manner exactly 

 like that of C.B. 4, e. Longitudinal sections show a gray cap at 

 the heavy outer end, a middle zone of yolk and an inner light 

 vesicular zone. The distribution of the "Keimhautblastem" 

 is also similar to that in an egg centrifuged with the opposite (pos- 

 terior) end toward the axis of rotation, i.e., it has moved toward the 

 lighter end of the egg. The inner pole is creased and folded as 

 in C.B. 4,^. One nucleus is present near the vesicular zone. The 

 pole-disc remained at the posterior end of the egg near one side; 



