m] CHROMOSOMES IN MITOSIS 37 



inner or central ends of the two halves diverge first, while 

 the two half-chromosomes remain in contact at their outer 

 ends, and complete separation does not take place until the 

 two halves have rotated apart until almost in line with each 

 other. The spindle-fibres are attached to the diverging ends, 

 and give the appearance of drawing these ends apart by 

 their contraction, while the opposite ends of the two half- 

 chromosomes remain in contact. The halves of V-shaped 

 chromosomes separate first at the angle of the V, and the 

 tips of the arms are the last portions to separate, so that in 

 early anaphase the dividing chromosome has a diamond or 

 lozenge shape. The spindle-fibres are attached to V-shaped 

 or hook-shaped chromosomes at the point of the bend. 



Very frequently all the chromosomes divide and the 

 halves travel to the poles quite simultaneously, so that the 

 two "daughter-plates" are very regular; this is so especially 

 when the chromosomes are of about uniform size. In other 

 figures some chromosomes divide and diverge before the 

 others, with the result that in anaphase they are scattered 

 rather irregularly over the spindle, some approaching the 

 poles before others have left the equatorial region. Some- 

 times one or more chromosomes constantly divide before or 

 after the remainder. These irregularities are most frequent 

 in the so-called maturation divisions of the developing 

 germ-cells; simultaneous division, with chromosomes very 

 evenly disposed in anaphase, is the common condition in 

 ordinary "somatic" cells. 



The formation of the daughter-nuclei from the groups of 

 chromosomes at the poles of the spindle in the telophase is 

 difficult to observe in detail because of the crowding of the 

 chromosomes. When, as often happens, the individual 

 chromosomes in the late anaphase become vacuolated and 

 take the form of small vesicles, the nucleus appears to 



