74H JOHN iJKAUi), 



In i)IunlH, so I'jir us is known, th(3 reduction of clirorriosonics pre- 

 ccjilcs the orif^in of the sexual gencinUion ; in aniniiils it succeeds the 

 coining-into-hein;,' of the hitter. In th(! one case the reduction iiapitens 

 prior to the foririiition of spores, in the other of gunietes. On the 

 view (jipparently luîhl l)y STUAHinjmjKit) of th(î occurrence of sex- 

 determiniition at the formation of spore-niother-cells the immediate 

 sequel is the |)roduction of a s(!xual or^^'anism, the ;^'iunetopliyt(!, witli its 

 }^erm-cell or (;ells. In animals the next (lonsefjucnce of tin; dilfercintiiition 

 of sex in tlu; oocyt(!S nnd s|»(!rm;i,tocytes is tlu; forniiition of f^atruites. 

 JVIor(!ov(!r, it is only after Mk; union of such ^'airuites, after the (hîvel- 

 opment of an asexual generation, or phorozoon, or larva, and aft(;r 

 the formation of a n(!W sot of germ-cells, that from one of these latter 

 a sexual org.'uiisin arises. 



Not only, therefore, is the period of the reduction of chromosomes 

 associated with that of tin; determination of sex, hut the said reduction 

 is immediîiUîly in both ajiimals and plants followcîd hy dir(!ct mani- 

 festations of sex, in the one instance the gametes, in the o(,h(;r the 

 ga,metoj»liyte. The two a,re tiius linked together. Where the one is 

 found at a certain i)oint in the life-cy(;le, there also is the other to be 

 (incountered. This point is apparently not tin; same in animals and 

 in plants '). 



diroctly wiUi l.lm r()r'iii!i,l,i(iii ol gainoios; nay, ovon to fo^iu'd tlio bringing 

 into existonco of tlioHO as thd real reason of the occurrence of a réduction. 

 Nor wuH it, M,t all obvious, that it might be asHociuted with anything 

 oIho. liAiri'oo haw urged, th;i,t, tlu» iniiiKirical reduction of cliroinoHoiiies 

 iH eertaird}' not uiiivorMa,! in tli(5 I'oi-inntioii ol" gametes (o|). cit. p. 54). 

 if the explanation of the moanin/i; of the reduction current among 

 /oologists be the correct and only one, wliy should an a,|)piu'ent ili- 

 mitintion in the nnmber ho Ion;/; |)r'(ic,<uie the actual accoiM|ibHliment of 

 tiio process V Why .should two nuclear diviHions be necesHary to 

 olfect it? 



Since the reduction i)recodeH tlio two final mitosoH, resulting in the 

 production of «gamètes, tli<t app(Miranc(i of the hitter- Ih the consequence, 

 not the (îauHc, of the reduction. 



\j The diil'erenco, however, is more apparent than real. In botli 

 cases the beginning is made between the asexual generation, the 8])oro- 

 phyte and phorozoon respectively, and what lollows this. To put the 

 Tiuittdr in anothor way, tlie commenccMncnt immedi!i,toly Huticoeds t,he asexual 

 f^oneration. In plantas IJki reduction and ilclormi nation ai'o at once bj'ought 

 to a linish, prior to any new appearance: jti animals lh() production ol 

 a gameto/oon intervenes between the commencement of the determination 

 and reduction, and the liniHli. 



