1898] ‘NUCLEAR REDUCTION’ ia 
tion of the sexual pairing cells. The extension of this by zoologists 
to all cases was tempting; and the demands of the Weismannism of 
the ’80’s made this extension appear imperative: reduction or ex- 
cretion processes in gametogeny were diligently sought for, and of 
course found everywhere; and in’91 (pp. 62-3) I enumerated and 
discussed as many as fifteen which had been accumulated in defiance 
of morphological homology or physiological equivalence. In the same 
paper, I discussed the question of nuclear reduction from the then 
state of our knowledge ; and pointed out that in Flowering Plants 
reduction occurs in the pollen-mother-cell, and that this is the 
equivalent of the asexual spore-mother- cell of Archegoniate 
Cryptogams (Ferns, Mosses, &c.). “We must remember that the 
reduction takes place in the pollen-mother-cells of Flowering 
Plants, which are themselves homologous with the mother-cells 
that form tetrads of asexual spores in Archegoniate Cryptogams ; 
hence we may be allowed to conjecture that reduction also takes 
place in the latter group; and by parity that it is not confined to 
gametogonia | =the mother-cells of a brood of gametes |.” 
At the time there was only one case, that of a liverwort, that 
had been at all fully worked out, but since then, we have learned 
that in the ovule of Flowering Plants reduction takes place at the 
first division of the primitive nucleus of the embryo-sac ; and that 
in the Archegoniatae without exception, reduction takes place at the 
inception of the formation of the tetrads of spores, not at that of sper- 
matozoa and oospheres, the equivalents of the sexual cells of Metazoa. 
Moreover the spore of Mosses gives rise to the leafy plant, capable of 
indefinite vegetative growth and propagation ; that of the Fern to the 
Fern-seale, which in Gymnogramme, for instance, is perennial also. 
Thus nuclear reduction is not a process that finds its explanation in 
the formation of cells specially adapted for ‘sexual’ (sit venia 
verbo ”) fusion or gamogenesis. 
I may be permitted to refer to my recent paper (97) for the 
exposition of the existence in Metazoa of a long cycle of colonial 
cell-divisions, alternating with a short one of protistoid brood- 
1°91, p. 57-8. The sentence closes thus: ‘‘but will be found in all mother-cells de- 
stined by multiple fission to give birth to a brood of reproductive cells.” Of course the 
latter part of the conjecture has not held good, but the former part has maintained 
itself : namely that reduction takes place in Cryptogams at spore-, not gamete-formation. 
The anticipation thus formulated by me in 1891 was repeated by Overton in 1893, and its 
enunciation has been ascribed to him by Strasburger ('94a, p. 291 ; ’94b, p. 825), while 
later the error has been continued by Wilson (’96, p. 196). I did not think such a 
question of priority worth noting by itself, but take this opportunity of correcting the 
mistake. 
? The word ‘ sexual’ has two distinct meanings ; the one relating to the fusion of two 
cells, &c., into one, the other the differentiation of such pairing-cells into two unlike 
categories such that cells of the one will only pair with cells of the other. ‘ Sex,’ ‘ sexual 
differentiation,’ ‘sexual processes,’ are terms as often used in the one sense as in the 
other ; and we may easily avoid the confusion by describing the former as ‘ pairing pro- 
cesses,’ or ‘ fusion processes,’ and the like, and using the additional adjective ‘ binary ’ 
with ‘sex,’ ‘sexual,’ to distinguish the latter meanings of the terms. 
