230 PLANT LIFE 
persists are the chromosomes. These bodies, 
as already indicated, take up a very definite 
position, and now lie in an equatorial plane 
half way between the two poles to which 
the spindle fibres converge. 
Each chromosome then divides longitudin- 
ally into two symmetrical halves, probably 
along the line of the parallel streaks of chro- 
matin described above. The two halves then 
diverge, and the daughter chromosomes at once 
retreat along the spindle fibres, to form two 
groups, one at either pole. The daughter 
chromosomes swell up, a nuclear wall is 
formed around them, some of the substances 
which escape from them run together and 
form new nucleoli, and thus the two daughter 
nuclei are formed. A cell wall is often de- 
veloped across the spindle which persists for 
a time between the two nuclei which have 
thus been constituted, and nuclear division is 
then followed by cell division. When the cell 
wall is not so formed, a binucleate, or later 
a multinucleate, arrangement is produced. 
The main conclusions that emerge from a 
consideration of the facts thus briefly out- 
lined are: (1) The number of the chromo- 
somes is constant, and individual peculiari- 
ties in form and size are seen to reappear 
whenever the chromosomes are sufficiently 
contracted as to become sufficiently clearly 
recognisable. (2) The chromosomes, when 
they divide, transmit their peculiarities to 
each daughter chromosome. In other words, 
