WATl'li;. I'lSSI'lN'I'IAI, TO AM, \AVK. 



227 



Tlic liHSiics ol'all |)l;iiils jiikI aiiiiii.ilH, in cirlv life, rdiiiaiii 

 linicli iiiorc^ watt r tliaii wIh-h (licy nrr lull ^Towii. In all 

 ji,T(t\viii;:,' ciiiltrydM 1 he laojyorlioii (•!" wal cr iH very coiiHidcraMc 

 'riiric i,s a, lii^lu'i' |)('i'ccnia|;-(i ol waicr in Hit- tisKncH of Wic 

 yoiiii;^- riiild llian in growth and in udiiK. lil't'. bjvcryonc 

 IciiowH li(t\v easily yoiiiif^' children are injured, in e(Miso(|uenee 

 of tli(^ Hdl'InesH ol' their iiasucN, e(tnHe(|Ue!'t, on Ihe lar;j;e 

 ])r(i|i(»r( ion of water |ti-eHen(. The Hanie icniark applicK to 

 many ol" lhoH(< unloi'tunate caseH which we see Ironi lime to 

 tinui where! local or }i,'encral jj;i-owth in ino rapid. 



In tinHUCH and orp,'anH which iucreiiHu with abnormal 

 rapidity, a Iarj2,(i luunbcr of l>io|>lastM in a, ;^iveu area, will 

 he i'ound, and thcHc coidain much w.iler and may divide 

 juid Hulxlivide and j^iow, very laHJ. ()n the other hand, 

 wIkui tisHUcH ini(lci';i,'o coudeuHatioii and in some foinis ot" 

 " (U^ocuiM'aiion," Ihey ar<i i'ound to coidain ii, much higher 

 ])crcenta^'c of Holid maH((r than thoHO which a,i"e healthy, 

 ^uid this point is of iutercnt to ]>liyHiciauH with r<'rerence (o 

 the hi^hcHt and mctst complex orfi,anH ol' uiaii. 



'The or;a,'!in which does Wn' most wonderl'iil iiuifk in all 

 Jivinjj; iia,tnrc, and tho hi^-hcHt work \\i' ourHclvcH are capahhi 

 ol", \H that part ol' tlu* l)ra,in Avhich is n(!ar the upper oulci- 

 Hurrace, ol' the cerebral convolut ioiiH. An I MUj)poMc cveiyone 

 knowK, there in a ;^'reat diirereu(!c in the brain ntructui-e in 

 diU'crcnt parls. Hroadly, tho cortical or outer parls of the 

 Hurl'acio hemiKphercH ol' tlic brain, ar<' i^'rey and are called 

 j^'rcy miitfer of iJic cerel)ral con volutions. TIuk is very 

 la,r^'cly supplied with blood, ihe xcsscIh bein^' ev<!rywhei'(! 

 very numerous. !>( iK'atli this outermost layer of the brain 

 Htru(!ture, is a consith'rable amount of brain tissue which is 

 of unu'h iirmcr consistence than the j^'rey mattci", and 

 suppli(Hl with far less blood, it is whit(ir in apjtcaraucc, 

 and here and thert! it cxhibitH lines, and has a distinctly 

 librous appearance. In the direction in which th<» lines run, 

 the tissue, which contains less waicr than the ;.^rey imittt^r, 

 may be in some cases (easily toi-n. The blood vc^Hsels in this 

 white maltcu', arc not numerous, and i\u', aniouid, of blood 

 distributcul to the ;^rey matter of tho convolutions is very 

 small in j)roportioH. 



In all the nerve "•centres," sonu-times on tho sui'fac(!, and 

 sometimes in the substiiiUH', is soil and vi'iy moist matter 

 which corresponds to the ji,'rey mat,t,er of the brain, and 

 contains many living' p,'rowin<j;' bio|)lasts — and matter which 

 is mucli lirmer and more libi'oiis — not a,(!tiially dry but 



