5i! 



R. W. Hegner 



TABLE II 



CaUigrapha higshyana — Series C.B. 4 



The progressive effect of a centrifugal force upon the distribution 

 of the contents of the egg is shown by these experiments. They 

 also furnish data concerning the amount of disturbance neces- 

 sary to prevent the hatching of a normal larva. 



C.B. 4, a. Sections of the fresh control egg of this series show a 

 condition similar to that illustrated in Fig. 9. 



C.B. /f-, b. An egg centrifuged for fifteen minutes is very 

 slightly affected. The "Keimhautblastem" has apparently not 

 been changed at all. The yolk shows a partial redistribution; 

 the larger, heavier globules have begun to move toward the outer 

 end of the egg, i.e., the end away from the axis of rotation, and the 

 inner portion of the yolk mass is almost entirely composed of the 

 smaller globules. The pole-disc occupies its normal position at 

 the posterior end of the egg; all about it are small, irregular vesic- 

 ular spaces which are no doubt caused by the accumulation of the 

 lighter fats in this region. No polar bodies could be discovered 

 in the sections of this egg, but no significance can be attached to 

 this fact as they cannot always be found in normal eggs. 



C.B ^, c. The effects of centrifugal force apphed to this egg 

 for thirty minutes are similar to those just recorded for C. B. 4, h.\ 

 the changes however are more pronounced. We find that there are 



