( 491) ) 



llio vnliic of llic well known Tlicnrv dl' llic liiston-ons dl' Il \nstki\. 



In workinu' (miI liis llicorv \ \\ TiiuniKM pnrposch .iNoidcd as 

 nincli as possiWlc lo make nsc dl' llic liislurv dl' (lc\('ld|ini('iil, and as 

 lias liccn |ti'd\('d jiisllv. \i'\ il was «inilc nalnral l(t tliink llial llicrc 

 was a cdnncclidn Wclwccn llic slrncnirc dl' the l'nll-urown slem and 

 i'ddl and llial dl' llic same oruans at a xcrv carlx pcridd of dcvcldpincnl, 

 in (Mnltrvd or urow inu' pdinl. i'^dr II \ns'|'|',i\ had «'slaMislicd a ddcli-inc 

 alidnl llic slrnclnrc dl' llic nicrislcnis, Ncrv niiicli like \ w 'rii;(,Mi:M"s 

 llicorv and had uaiiicd a nnnilxM' dl' adhci-cnls. I Ie Ihdiiuhl . cspccialh 

 on accoiinl of llic ari-aimcniont ol' Ihc dlhci-wisc (Mpiixalcnt cells, l(» lic 

 alilc ld disliimnish llircc tissues in those inci-islcnis, called dcnnalo;i'cii, 

 pei-il)leiii and pleroine. The last \\a> a coliiinn ol' cells in the middle 

 part dl' the slem and root. ( )!' cdiirsc il was (pnlc nalnral ld think 

 ol' an idenlitv ol' dei-inalo,u'cii and cpiderinis, periltlein and cortex, 

 pleroine and ccnlral-cvlindei'. in micIi a inaiiner that the latter had 

 <le\"cldped ont ol' the t'oi-iii<'r. H' it were |)ossilile to |)oint o)il sncli 

 a correspondence, this would he for the Stelai--theor\- as well as for 

 llie Theorv of the histoiicJis of i>i-eal iinportaiice, thoiiLiii not (ifeipial 

 iniporlancc Uw liolh. If the cenlral-cvliiider is alread\ fdiind in the 

 in(M-isl(Mn as an independent whole, ihis points lo the fact, that the 

 dill'ei'cnlialidn of this tissue is old a]id then the Sl(dar-tlicdr\ has 

 .uained aiidthei- siippoi'l. lint as I said alidxc, il is fnllv estaldished in 

 andlher w a v and can xcm'v well do wilhont this snppdi-t. 



The II ANSTKiN-lheorv of the histdii-ens is a dilfercMit cas(>. K\-er\(»ne 

 who studies the iiteratni'c inipai'tiallv, will liaxc to own that this 

 doctrine I'c^sts o]i a \'erv weak foinidatioii. pérlia|)s not with respecl |o 

 the derniatouon, hnl vovy cei'taiidv as far as the pleronie is concerned. 

 Il is true, there are some roots and a \'erv few stems in whose ihin tops 

 the cells are arranu-ed in a reniarkably reunlai' oi'der, so Ihat a ceiilral- 

 cvlinder can he distinLinished as pleronie. Hnl in niaiiv i-oots and in 

 neai'lv all stems lliei-e is no (piestion ahont traciiiu' sncli an arraiiu'e- 

 meiit np to the urow inu-point. It is reallv to he wondered at lliai 

 this 1 1 \Ns'i'KiN-lheoi'v in its uciieraldv has found so inan\ Pennine 

 adherents: this is certainlv partiv ow iiiü' to the cdn\ictidn. expressed 

 l>v manv and silenllv shared liv dihers, that plerome and ceiitral- 

 cvlinder are one and the same. 



^ ct this had ne\<'r heen accnratelv examined till il w as nnderlakeii 

 liy Mr. SciioiTK. Ihit il is clear, that a positive result would he of 

 ihe grealesl importance for this theory. I-'or there is no sense in 

 acceptinu- hisloiicns wilhont fiill-iirown tissnos correspondinLi' lo llieni. 

 Aloi-eoNcr niiuht l»e expected of a positive i-esnil the possihilit\ of 

 tiiidiiig an njjdonhled plerome when folluwiiiu- tiie hoiiiidarv of 



