THE SPINDLE 27 



plane as though in a flat plate. Where they are long, relative to the 

 size of the spindle, the limbs of the chromosomes remote from the 

 centromere lie at random — equatorially or axially. But owing to 

 the spindle space being limited, the limbs of long chromosomes on 

 the edge of the spindle lie in the outer cytoplasm, and the bends at 

 their centromeres therefore point inwards. In many animals, all 

 or most of the centromeres lie on the periphery of the spindle ; 

 the distal parts of the chromosomes then lie wholly outside the 



Fig. 5. — Metaphase plate in Puschkinia lihanotica (2n = 10 4-4#)- 

 R. and L., relational coiling of chromatids, /, supernumerary 

 fragments, a, m and 5 have secondary constrictions. (D. 1936 b.) 

 X 3,000. 



spindle, and in living cells {cf. Belar, 1929, a and h) can be seen to 

 move in the streaming cytoplasm. In this way the chromosomes 

 may fill up the greater part of the cell space. 



Until metaphase, the chromatids are held together less closely 

 elsewhere than at the centromere. The momentary condition of 

 " full " metaphase is reached when the limbs of the chromosomes 

 have come together as closely throughout their length as they were 

 earlier at the centromere. It may be imagined that the stage 

 with the distal parts of the chromosome separate follows this stage 

 with the closest association, and is actually the first stage in the 



