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Vol. 16—1962 - NorthEastern Weed Science Society

Vol. 16—1962 - NorthEastern Weed Science Society

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2S<br />

J<br />

complex moleculail" architecture<br />

o.f the cell.<br />

I would like to show you tiNt a pictUi'e' 1)£.a cell in the root tip at<br />

maize. This is a transverse sect1on~ l75p, trom.the apex. T~e large.c~<br />

tral bodY is t.be nucleus with the darker c~1ft aNa8'andnumerou, Pclres<br />

in the double ,nuclear membrane. "The elongated c~ ·~through 'the<br />

cytoplasm are portiOns :of the lIlidOplasm1oretioUlliifirwl\ioh represent,Pt'ojectionS<br />

of'theriuolear doilblemedSrane •. The :nUllllili'OIls olub sba,pedor.· .<br />

106undedbodies Withintemal pro~cti6ns are thftlli1~ohondria with their<br />

cristae. The' grouPsdt sh61't ~swith veliliOUlul:.rIds&re Colgi bodie •• ,<br />

The lighter stipPled-apPeai'1ns~sin' the ti~pWin ,are the vacuole$.:, .;..<br />

Certa1nlyth1sia a beautiful 8rii "canplex maohifte~d'ItJ represents a strU.~<br />

ture towl'li Mial.l1'h7siologioal'data must be %',ete1,i8d'ff, indeed, we ~ to<br />

understand what we are tal1d.ng a~ut. .,". .<br />

In addition tothenumerousoytoplasmio structUre1swhich wehave jUst .<br />

seen, the plant -oell also posed"s a complex cell! will which is physic~<br />

quite rigid during lIIOstof the dtrveloJXDllntof tl'~;'beU arid ooilstrains the.<br />

protoplast frOlnexparvH.ng undet' the intlilenceot lnti!lrnal turgor pres~.<br />

Chem1cantthi~ 0.1;]. walloons18ts of'such mat~us' ¥ pectin,. polysaoc~ ,<br />

rides of "aMolis 'types (including cellulose), lignins, and proteins •.. T~_<br />

plant o;VtolOS!st, 11Sing light,lIlfoiQscopy, has b~'"abJ,eto dist1n~s~. ~. '<br />

middlelameUa-which we novibe:l;ieve to be mairily p'~ctin ~ nature, a p~<br />

wall which iis pl'ii:lllirily 'oellulosi'c and a secondart'·;,au which may oont4n,<br />

almostantthing. : This wall is'tx'Ucturemaybe contllulbu is but it is usuai.l.;r ,<br />

perforated by numerous pits am holes and electron mi~rroscopy has revealed<br />

thatoytoplasmio strands and perhs,ps even branohes .Of the endoplasmic 1!etioulUlllrUnfran<br />

'cell to cellth~~these per{ora,t1~ -. Thus, despite i~.<br />

separli.'tio~ into ~sorete wOoden'}ld~s,the l1,v1ng,.partof the plant bodr:<br />

does represent a p~toplasaa,~ cb,htinuum; thereap~!I to be easy 00lllllW1ice,..<br />

tion between cells by means of" their cytoplBSJlliq ,oQnnections.,<br />

~

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