476 Farmer . — On Spore- Formation and 
There are formed eight of these aggregation or condensation 
groups, and they ultimately give rise to the eight chromo- 
somes characteristic of the gametophyte of this plant The 
longitudinal fission of the chromosomes occurs during this 
stage. The aggregations just mentioned lengthen and are 
then clearly seen to be double. Indeed the longitudinal 
halves are often so distinct that I believed at first that 
a fusion of two separate chromosomes, and not the fission of 
one, was taking place. Each half is very clearly seen in 
favourable cases to be only a local thickening in the linin, 
the thin and comparatively uncoloured portions still con- 
necting one chromosome with another. The swollen parts 
of the linin, to which the chromatin is chiefly restricted, then 
contract, and form the eight intensely staining bodies which 
are situated just within the wall of the otherwise non-staining 
nucleus. As they contract, the longitudinal character of the 
fission becomes more difficult to discern. The chromatin is 
often seen to be grouped in a singular manner at this stage 
(Figs. 5-7) when the chromosomes happen to be regarded- 
from one end. Sometimes four such aggregations could be 
seen in each chromosome, but the number was not sufficiently 
constant to afford very secure ground for theorising. At the 
same time the appearance was such as to suggest that a double 
longitudinal fission may take place here, and thus the next 
(and final) division may be prepared for. Such a case has 
been described by Brauer for Ascaris , and some of his figures 
bear a striking resemblance to what is seen at this stage in 
Fossombronia. But the question can only be settled by 
a study of a far larger amount of material than I had at my 
disposal. The process is passed through so rapidly that 
several hundred preparations may be examined without 
finding the exact stage required. Finally all the unthickened 
parts disappear, and the chromosomes then appear as either 
solid structures or else as ring- or ellipse-shaped bodies lying 
within the nucleus. They become more dense still before the 
advent of the achromatic spindle, all signs of any longitudinal 
fusion become obliterated, and they gradually assume the 
