228 PLANT LIFE 
same time the chromatin increases in quan- 
tity. Stains of various kinds show that the 
chromatin-containing strands are, as_ it 
were, becoming individualised within the nu- 
cleus, although anastomoses between adjacent 
strands are still of common occurrence. As 
the strands continue to differentiate, the 
chromatin is seen to form two parallel streaks 
in the convoluted linin bands, but this duplex 
appearance becomes temporarily obscured, 
though not obliterated, at a somewhat later 
stage. Each one of these duplex chromatin- 
containing linin bodies is achromosome (Fig. 26). 
When fully formed, the chromosomes assume 
the form of rods, hooks, ete. The most strik- 
ing point about the chromosomes lies in 
the fact that their nwmber is normally quite 
constant for a particular species of plant. 
The chromosomes become clustered in a 
very characteristic position, and form a zone 
or plate across the centre of the nucleus; but 
preceding this arrangement, and intimately 
connected with it, a remarkable spindle-shaped 
structure arises in the extra-nuclear proto- 
plasm (cytoplasm). It is made up of fibres 
which are ultimately arranged in very much 
the same curves as iron filings take up when 
scattered on a piece of paper under which lie 
the poles of a horseshoe magnet. The spindle- 
like structure extends across the space origin- 
ally occupied by the nucleus, while the wall 
of the latter usually (but not always) dis- 
appears, and the only nuclear structure that 
