INTERCELLULAR CANALS IN niCOTYLEDONOUS WOODS 439 



SUMMARY 



Intercellular canals are shown to occur in the secondary wood of 

 representatives (mostly tropical) of sixteen families of dicotyledons, 

 namely, Hamamelidacese, Rosacese, Leguminoseae, Rutacese, Simaru- 

 bacese, Burseracese, Meliacese, Anacardiaceae, Bombaceae, Dipterocar- 

 paceae, Combretaceae, Myrtaceae, Araliaceae, Styraceae, Boraginaceae, 

 Compositae. Many of these have not been previously reported. 



In some cases the canals are normal features of the wood ; in others 

 they develop pathologically. Woods with normal canals may have 

 others produced as a result of injury. 



Canals may be vertical only, radial only, or very rarely in both planes. 

 The radial canals are contained in the medullary rays, and vary in num- 

 ber from one to four. 



In origin the canals are schizogenous, lysigenous, or schizo-lysigenous. 



The secretory canals in dicotyledonous woods afford numerous par- 

 allels to those in gymnosperms, but in many important features are 

 Cjuite distinct. 



The secretions in dicotyledonous woods exhibit a wide range of vari- 

 ation, being resinous, oily, gummy, or tanniferous, as opposed to the 

 conifers in which the secretory products of the wood are wholly 

 resinous. 



The presence of intercellular canals in a wood serves as a valuable 

 diagnostic feature. It was from this point of view, rather than with 

 reference to the origin of the canals and to the nature of their contents, 

 that this study was made. 



LITERATURE CITED 



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t. i6, No. 3, 1902, p. 69. 



2. Solereder, Hans: Systematic anatomy of the dicotyledons. Oxford, 1908. 



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