KARYOKINETIC FIGURES OF CENTR1FUGED EGGS. 



JO/ 



nearer the animal pole and thus exerts pressure on the spindle. 

 Many cases of this kind are found. 



If the animal pole is distal in position in the centrifuge the 

 spindle must be subjected to rather violent assaults : first, because 

 its specific gravity tends to drive it towards the opposite end of 

 the egg ; second, because the basophile granules are streaming 

 away from it and the acidophile granules rushing in, and third, 

 because the inner dense zone is approximated to this pole (Fig. 

 4, />). I have not found any eggs with the spindle fixed at the 

 distal pole after centrifuging, and am therefore forced to assume 

 that in all cases in which the centrifugal force acts in this direc- 

 tion the spindle is torn loose from the surface and moves up into 

 the hyaline band. 



1 



A B 



FIG. 4. A, diagram of the zones of the ground substance in the normal egg and 

 the relations of the spindle. B, diagram to illustrate the effect of centrifugal force 

 on the ground substance and spindle acting in the direction of the spindle. Num- 

 bers and letters as in Fig. 3. 



Intermediate directions of action of the centrifugal force will 

 affect the protoplasm and the spindle in ways easy to deduce 

 from the above. 



If the above analysis of the effects of centrifugal force is cor- 

 rect, or even partially so, we have to distinguish between those 

 cases in which granules are driven out of, or into, the area of the 

 karyokinetic figure, and those cases in which the spindle has 

 moved its position. It is obvious that both conditions may occur 

 simultaneously ; indeed, it is probable that this is almost always 

 the case. 



