lv.. 8] 



1 NUCLEAR REDUCTION' 117 



tion of the sexual pairing cells. Tin' 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 every where ; and in 'D 1 (pp. 62-3) 1 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 1 [ = 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-scale, 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 veuia 

 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 tission to give birth to a brood of reproductive cells. 1 ' 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 atspore-, not grawiete-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 

 mi.-take. 



-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. 



