No. 60G] 



BIOLOGICAL KXIGMAS 



341 



enz^-me for orpuiic n'milalloi! w.- iimst of course recop:- 

 nize that the exact cflccis ] Mixhiccd by catalysis depend, 

 at all stages of d('\'('l()i»in('iil. upon the manner of its co- 

 operation witli other [)hysical ])rin(ni)les, wliich may in- 

 volve the functioning- of molar structures already in-es- 

 ent. Jlowever, as we retrace the course of ontogeny and 

 of the evolution of any specific germ-cell, we should find 

 that the number and iniy)ortance of such structures de- 

 crease, although the construction of any given tissue- 

 form always depends upon the action of specific enzymes 

 in conjunct ion with ])reexi sting tissue sti-uctures. It is 

 not to be doubted for an instant that important |)re('stab- 

 lislied structures exist even in germ-cells, and enter into 

 the determination of their activity. It is tlierefore un- 

 fair to demand a catalytic exi)hiiiation of such a comi)h^x 

 process as karyokinesis, whicli slmll not take into con- 

 sideration the history or evolution of tlie cell. 



^riic tnsk of elucidating the exact mcchnnisiii liy means 

 of which vital I'cgulation is maintained, and rs|nM'inll\- dl' 

 showlnu' how. in accordance with rec(ti:iii/t'il ] .i-i nci plr- 

 of |.h>^h-. a comi^lex of vpocitic. antnrataK tir. mlhudal 

 paiti.'h- In Ihc ucnn-ccll can cPuin.M.r U r c.nM rn.-tion 



unkind for the vitali^t arbitrarily to deny n^ the n^c of 



nu'iM be ju'iinitted In MippuM- that a laru- ran'ber of 

 variable. ,-an un.te in th." pr..dnrt ion o\ a ^ii-le . tVrrt. 

 Theureat. r i-art ..f the ni.ulern Nitali^tir won\ oN.-r ••(M• 

 l;ani7at ion ' ' and \ita! -e.|"iiihrinin ai-jM-ar^ tn d.-]K'iid 



reliable, or that it l inii.o.^lbh. 1 o,' a' ]inml)er ..f variables 



assumptions are sol I'-cvideiitlx' (M)nntei' to tlie nio-t Innda- 

 mental presuppositi(ui- of physical analysis. 



Although the fundamental life i^ropeHy ,,f tlie .chro- 

 matin units is that of antocatalv-is. it i> no(T-<ar\ and 

 legitimate to suppose that tlu' itia i.)i-lt\- of thcin -intain 

 specific heterocatal\ tie relationships to reaction- oc- 



