INTERCELLULAR CANALS IN DICOTYLEDONOUS WOODS 

 By Samuel J. Record 



There are many representatives of the dicotyledons whose woods 

 contain intercelhilar canals having contents which are resinous, oily, 

 gummy, mucilaginous, or tanniferous. In some instances — for exam- 

 ple, in the Dipterocarpacese and certain Cassalpinioidese — such canals 

 occur normally and are characteristic of all large stems. In others, 

 ducts arise only in consequence of injury, and thus may be only occa- 

 sionally observed. In general, dicotyledonous woods containing secre- 

 tory canals are confined to tropical or subtropical regions. 



In some woods the canals are all vertical or axial ; in others all hori- 

 zontal or radial ; but in no case has the writer observed them in both 

 planes in the same wood, although a few instances of such have been 

 reported by others. Herein they differ from the conifers, since in the 

 coniferous genera in which resin ducts occur normally (Piniis, Picea, 

 Pscudotsuga, Larix) they are invariably disposed in both planes. In 

 consequence of injury, traumatic vertical ducts often originate in the 

 cambium of these four genera, and also in Sequoia, Abies, Tsuga hete- 

 rophylla, and Cedrus, which are normally without resin canals in their 

 secondary wood. Such ducts are disponed in tangential series, as in 

 the dicotyledons, and may anastomose more or less. Traumatic radial 

 canals are uncommon in conifers, but have been noted in Cedrus and in 

 certain extinct species of Sequoia, although always in association with 

 vertical ducts. In dicot34edonous woods, traumatic radial canals may 

 arise independently of the vertical ones, as observed by the writer in 

 a young stem of Schimis iviemnannifolius, but in other instances — 

 namely, Styrax benzoin — both vertical and horizontal ducts may arise 

 as a result of injury. Sometimes the effect of wounding is to produce 

 secretory pockets corresponding to those found in coniferous woods. 



Whereas in coniferous woods the normal vertical ducts are dispersed 

 or in tangential groups of 2-3, in dicotyledonous woods the normal 

 vertical canals are usually arranged in tangential series, sometimes pro- 

 ducing more or less complete concentric circles on cross-section, giving 

 the effect of growth rings {Dipterocarpacccc, Copaifcra, etc.). Again 

 the tangential rows may be very short, or the ducts may be in tangential 

 series in some portions and scattered in others {Drimycarpus, Dauicllia, 

 etc.). Traumatic canals are disi)oscd tangentialiy, sometimes in a dou- 



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