NUCLEAR DIVISION WITHOUT CELL-DIVISION. 1/5 



standpoint is that " during the telo phase the egg frequently becomes 

 am&boid, and may even make an abortive attempt to divide. 

 In the later stages in some cases it may actually divide into a 

 number of irregular masses, only one of which contains a nucleus 

 (Fig. 8, /), but which here again completely fuse together." 

 These phenomena are almost unquestionably the result of an 

 alteration of surface-tension ; at all events they are precisely 

 what might be expected to occur if such alteration in surface- 

 tension were to take place. It may therefore be regarded as an 

 established fact of observation that during the chromatic nuclear 

 phase certain influences are active which produce alterations in 

 the surface-tension of the egg. That these influences are of an 

 electrical nature may, in view of the above facts and consider- 

 ations, be regarded as at least highly probable. 



The increase in the surface-area of the egg during division 

 may be held to denote a general decrease of surface-tension. But 

 a perfectly uniform decrease of tension over the entire surface 

 could lead to no change of form ; this is evident from the fact that 

 fluid droplets of unequal surface-tension alike tend to assume the 

 spherical form when under the sole influence of such surface- 

 tension, provided this is uniform at all portions of the surface. 

 Changes of form in such droplets result when the surface-tension 

 becomes unequal at different regions of the surface. Thus if the 

 tension is lowered over a small circumscribed area (as appears 

 for instance to occur in the egg during the formation of the polar 

 bodies) the fluid tends to flow outward or be pressed outward at 

 that region the internal pressure being there insufficiently com- 

 pensated for the retention of the spherical form --and an amoe- 

 boid projection is the result. Perfectly definite changes of form, 

 such as occur in cleavage, imply a correspondingly definite local- 

 ization of the areas of lowered surface-tension. In the case of 

 the egg various indications --such, for example, as the prelimi- 

 nary elongation in the direction of the spindle-axis --point to the 

 conclusion that surface-tension is primarily lowered at the two 

 sides of the egg opposite the astral centers. From the position 

 of the asters during the metaphase and telophase it is to be ex- 

 pected on the present theory that the surface negative charge 

 will be densest near the regions adjoining the long axis of the 



