180 



ON THE INTERNAL FORM AND 



[CH. 



in a peripheral equatorial circle (Figs. 48, 49). This is precisely 

 what actually takes place. Moreover, before the breaking up of 

 the nucleus, long before the chromatin material has broken up 

 into separate chromosomes, and at the very time when it is being 

 fashioned into a "spireme," this body already lies in a polar field, 

 and must already have a tendency to set itself in the equatorial 

 plane thereof. But the long, continuous spireme thread is unable, 

 so long as the nucleus retains its spherical boundary wall, to 

 adjust itself in a simple equatorial annulus ; in striving to do so, 

 it must tend to coil and "kink" itself, and in so doing (if all this 

 be so), it must tend to assume the characteristic convolutions of 

 the "spireme." 



After the spireme has broken up into separate chromosomes, 

 these particles come into a position of temporary, and unstable, 



Fig. 52. Chromosomes, undergoing splitting and separation. 

 (After Hatschek and FJemming, diagrammatised.) 



equilibrium near the periphery of the equatorial plane, and 

 here they tend to place themselves in a symmetrical arrange- 

 ment (Fig. 52). The particles are rounded, linear, sometimes 

 annular, similar in form and size to one another; and 

 lying as they do in a fluid, and subject to a symmetrical system 

 of forces, it is not surprising that they arrange themselves 

 in a symmetrical manner, the precise arrangement depending 

 on the form of the particles themselves. This symmetry may 

 perhaps be due, as has already been suggested, to induced 

 electrical charges. In discussing Brauer's observations on the 

 splitting of the chromatic filament, and the symmetrical arrange- 

 ment of the separate granules, in Ascaris megalocephala, Lillie* 



* Lillie, R. S., Amer. J. of Physiol, viii, p. 282, 1903. 



