Chromosomes in Living Organisms. 295 
which lead up, on the one hand, to the development of the 
numerous spermatozoids in the antheridium, and, on the other, 
to the development of the single ovum in the archegonium, 
differ both in the number and in the succession of the divisions. 
It is therefore impossible that the divisions taking place in the 
sexual organs can be of importance in the direction of ensuring 
equivalence of the sexual cells in preparation for the sexual 
act. Nor does a process of any kind whatsoever take place 
by which an equality in number of the chromosomes in the 
nuclei of the sexual cells is secured : this number is fixed 
once and for all in the mother-cells of the spores. It may 
therefore be concluded with regard to Osmunda regalis , and 
doubtless also with regard to all Ferns, that the nuclei of the 
sexual generation contain only half as many nuclei as do 
those of the asexual generation. Nor can there be any doubt 
that in the Ferns the sexual generation is the older : the 
second arose by progressive phylogenetic differentiation of 
the product of the sexual act after the first had become 
sexually differentiated, and hence its double number of 
chromosomes. 
With regard to the Muscineae, the counting of the chromo- 
somes has recently been undertaken by J. Bretland Farmer 1 . 
He found in Pallavicinia decipiens , a Liverwort from the 
mountains of Ceylon, that the dividing nuclei of the sexual 
generation (gametophyte) each contain four chromosomes. 
In the asexual generation (sporophyte) Farmer counted eight 
chromosomes in the nuclei ; and he further ascertained that 
the mother-cells of the spores have only four chromosomes in 
their nuclei, so that a reduction by half of the number of the 
nuclear chromosomes must take place in these cells. The 
mother-cells of the spores increase considerably in size 
previously to division, and at the same time become tetra- 
hedrally four-lobed. Between the lobes, septa grow inwards 
towards the centre of the cavity ; and a four-poled spindle is 
1 Studies in Hepaticae : On Pallavicinia decipiens , Mitten, Annals of Bolany, 
Vol. viii, No. XXIX, March, 1894. 
X 
