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. fig. 4). The structure of 

 these is explained under the head of PITTED 

 STRUCTURES. It must be understood, how- 

 ever, that the peculiarity of Coniferous 

 wood does not depend on the presence of 

 these, which 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 silicified wood, in which 

 almost all trace of organic matter is lost, 

 the silica forming complete casts of the 

 microscopic structures. This 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. fig. 33). 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 

 lead to misconception, appears to be that of 

 the wood of certain Magnoliacese, such as 

 Drimysj Sphcerostema, and Tasmannia, where 

 there is likewise absence of ducts and ves- 

 sels, while the prosenchymatous cells have 

 bordered pits ; out the wood differs consi- 

 derably in the character of the medullary 

 rays, and in the number and arrangement 

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

 WINTERED.) 



The wood of many of the 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 Taxus and Tor- 

 reya both are devoid of them : where 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 pectinata. 



The following analysis of the structure of 

 the wood of some of the most important, is 

 slightly modified from Hartig : 



A. Cells of the pith mth thin walls. 

 a. Liber-cells in cross-section broad \ 

 and mostly short, isolated in scat- f A ____ _ 



tered groups, or in bandit ofseoe- f* Blf 

 ralrows, or wanting ............... / 



*Wood with turpentine -canals. 



t Medullary rays with varying pits Pinvs. 

 ttMedullary rays with uniform 

 pita. 



^Cords of secretion-cells at the 

 outer limitof the annual rings. 

 $Outer wood-cells of the an- ) f, . 



nual rings smooth within... | 

 Outer wood-cells of the an-"| 

 nual rings with an obscure \Larii. 

 spiral fibre ..................... J 



1 1 Wood without isolated rows } . n 

 of secretion-cells .................. I**** 



**Wood without turpentine-canals. 



t Medullary rays with distant pits. 



J Wood-cells with distant pits, 1 



or 2 rows in pairs ............... 



H Wood-cells with crowded pits, 

 1-5 rows, in spiral arrange- 

 ment. 



} Ounninghamia. 



b. Liber-calls with square or oblong^ 



cross-section, in concentric rows, ( TAXINE.E and 



alternating with parenchymatous ( PoDOCARPKjE. 



cells ....................................... ) 



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

 **Pith without thick-coated liber- 

 cells. 

 t Wood-cells with openly-coiled 



spiral fibre ........................... 



ft Wood-cells smooth within. 



JLiber-layers with thick-coated 



JJLiber-layers without thick- ) 

 coated cells ........................ j 



B. Cells of the pith with thick walls, 



liber-cells square .................... . 



*Liber-cells without pit-canals. 

 tPith with a roundish cross-sec- ) 



tion, bark without turpentine- > Taxodium. 



canals ................................... j 



ttPith with quadrangular cross- j 



section, bark with turpentine- J- Thuja. 



canals .................................... ) 



**Liber-cells with pit-canals. 

 t Wood-cells smooth inside. 



TPith 3-angled ........................ Junipena. 



JPith 2- or 4-angled ............... Cupressus. 



t Wood-cells with a spiral fibre, ) rafrffi . 



like Taxus .............. 7. .............. ^Calhtns. 



BIBL. Goppert, De Conifer. Struc. 1841 ; 

 Anat. Magnoliac. Linnaea, xvi. 135, Ann. 

 Sc. Nat. 2 sr. xviii. ; Hartig, Botan. Zeit. 

 vi. 123, 1848 ; Schacht, Pflanzenzelle, 435 ; 

 Henfrey-Masters, Sot. 358, 625; Sachs 

 Sot. 496. 



CONIO'CYBE, Ach. A genus of Cali- 

 ciei (Lichenaceous Lichens), distin- 

 guished by the yellow powdery thallus, 



