CONIFERS. 



[ 202 ] 



CONIOCYBE. 



microscopic structure, is the condition of 

 the stems of these plants. The wood is 

 entirely composed of prosenchymatous cells, 

 of large size, without intermixture of ducts 

 or vessels; and those walls of the cells 

 parallel with the medullary rays (very 

 rarely those at right angles) are marked 

 with one or more rows of the peculiar bor- 

 dered pits which have been wrongly called 

 glands (PI. 1. lig. 4). The structure of 

 these is explained under the head of Pitted 

 Structures. It must be understood, how- 

 ever, that the pecidiarity of Coniferous 

 wood does not depend on the presence of 

 these, Avhich are common, but on the simul- 

 taneous absence of ducts. The wood of the 

 Yew presents in addition a spiral fibre, be- 

 tween the coils of which the pits lie. (See 

 Taxus.j These peculiar conditions of the 

 wood render it possible to identify it in 

 microscopic sections in a recent, and, if 

 tolerably well preserved, even in a fossil 

 state ; "the Coniferous structure may be 

 readily detected in silicihed wood, in which 

 almost all trace of organic matter is lost, 

 the silica forming complete casts of the 

 microscopic structures. Tliis is beautifully 

 seen in some silicified wood brought from 

 Australia by Dr. Hooker, parts of which 

 are so friable, that microscopic sections 

 may be obtained by splitting it with a 

 knife (PI. 25. tig. ;J3J. With solid silicified 

 wood, sections made by the lapidary are 

 required. We have also readily detected 

 the structure in Coal by the process we 

 have given under that head. 



The only case of a structure approaching 

 near enough to that of Coniferous wood to 

 leail to misconception, appears to be that of 

 the wood of certain Magnoliacere, such as 

 JJrimys, Sphcerostema, and Tasmantiia,\yhe\'e 

 there is likewise absence of ducts and ves- 

 sels, while the prosenchymatous cells have 

 bordered pits; but the wood difiers consi- 

 derably in the character of the medullary 

 raj'S, and in the number and arrangement 

 of the pits on the Avails of the cells. (See 



WiNTEREiE.) 



The wood of many of tlie Conifers is 

 traversed by turpentine- canals, which are 

 large intercellular passages bounded by 

 thin-walled cells ; in others these occur 

 only in the bark, while in Ta.ius and Tvr- 

 reya both are devoid of them : wliere none 

 occur in the wood, there are generally iso- 

 lated rows of cells filled with secretions ; 

 but not even these occur in the wood of 

 Abies pcctinata. 



The following analysis of the structure of 

 the wood of some of the most important, is 

 slightly modified from Ilartig : — 



A. Cells of the pith mth thin walls, 

 a. Liber-cells in erofs-seclion broad \ 

 and mostly short, isolated in scat- (. a „,pt,,„b. _ 

 tered(jroups,orinbands ofseve- j'-a-amnNH.*.. 



ral rows, or wanting / 



*Wood with turpentine -canals. 



t Medullary rays with varying pits Pinus. 

 ttMeduIlary rays with uniform 

 pits. 



jCords of secretion-cells at the 

 outer limitof the annual rings. 

 §Outer wood-cells of the an-} p^j„,, 

 nual ringi smooth within... ) '-'™"'*' 

 ^^Outer wood-cells of the an-] 

 nual rings with an obscure >Larix. 



spiral fibre J 



JJWood without isolated rows } -p- 



of secretion-cells ^Jricea. 



**Wood without turpentine-canals, 

 t Medullary rays with distant pits. 



I Wood-cells with distant jjits, I I aj  



or -J rows in pairs ^^ces. 



II Wood-cells with crowded pits, 

 1-5 rows, in spiral arrange- 

 ment. 



4Wood without cords of se- ) > 

 cretion-cells \Araucana. 



5$ Wood with cords of secre- I n „■ i 



tion-cells \Cunninghamia. 



ttMeduIlary rays with crowded l j-. 



pits 



ara. 



b. Liber-cf.Us with square or oblong \ 



cross-section, ui concentric rows, ( Taxine.E and 

 alternating icilh parenchymatous rPoDOCARPE/E. 

 cells J 



*Pith with thick-coated liber-cells . Salisburia. 



**Pith ^Yithout thick-coated liber- 

 cells, 

 t Wood-cells with openly-coiled ) m 



spiral fibre j-iaUTttS. 



tt Wood-cells smooth within. 



TLiber-layers with thick-coated ) ■„ , 



* Pi.lls . ^Podocarpus. 



TTLiber-layers without thick- \ -r, ,. 

 coated cells \ Dacrydmm. 



B. Cells of the pith tcith thick walls, ) « 



liber-cells square ; [CUPEESSINE.E. 



*Libcr-cells without pit-canals. 

 tPith with a roundish cross-sec-) 



tion, bark without turpentine- r Taxodium. 



caniils ) 



ttPith with quadrangular cross-) 



section, bark with turpentine- >• r^K/n. 



canals J 



**Liber-celIs with pit-canals. 

 tWood-cells smooth inside. 



JPilh ;!-angled Juniperus. 



JPith 2- or l-angled Ciipressus. 



t\Voi)d-cell8 with a spiral fibre, ) „ „., . 



liker«x«^ : '\Calhtris. 



BiBL. Goppert, Be Conifer. Stnic. 1841; 

 Anat. McKjnoliac. Linnsea, xvi. 135, Aim. 

 Sc. Nat. 2 ser. xviii. ; Ilartiir, Botan. Zeit. 

 vi. 12M, 1848; Schacht, Pfiunzenzelle, 435; 

 Ilenfrev-Masters, Bot. 358, U25; Sachs, 

 Bot. 40('). 

 _ CONIO'CYBE, Ach.— A genus of Cali- 

 ciei (Licheuaceous Lichens), distin- 

 guished by the yellow powdery thidlus, 



