432 JOURNAL OF FORESTRY 



fleck, they enlarged slightly, and then narrowed to a tiny space between 

 the cells, and next disappeared. This is in substantial agreement with 

 the observations of Trecul (3) on Rhus viminalis, the only representa- 

 tive of the Anacardiaceae in which he noted canals in the rays. 



Some woods contain secretory cavities instead of canals, a cavity 

 being an intercellular secretory space spherical or ellipsoidal in shape 

 and having contents which are not mucilagenous. According to Sole- 

 reder (2, pp. iioo-i), irregular secretory cavities developed by the dis- 

 organization of portions of the tissue of the wood have been recorded 

 in Bvodia and Xantlioxylum (Rutacese) ; Carapa (Meliaceae) ; Dilo- 

 dendron (Sapindacese) ; Burkea (Csesalpineae) ; Terminalia (Combre- 

 tacese). (See also discussion under "Compositse.") "With this feat- 

 ure we may associate the formation of tragacanth in the species of 

 Astralagus and the occurrence of gummosis in the species of Acacia 

 and in the Prunese." (Solereder, loc. cit.) 



Mention may also be made of mucilage canals and cavities. The 

 cavities have been observed, according to Solereder (2, p. 1099), i^i the 

 wood of Bvodia rutcrcarpa and Xantlioxylum budrnnga (Rutace?e), 

 while mucilage canals have been found in the wood of Herminiera 

 (Papilionatae), and sometimes in the wood of certain Sterculiaces. 



These canals and cavities, which are intercellular, are not to be con- 

 fused with laticiferous tubes, which are elongated, branching, non- 

 articulated cells with contents of a varied nature, such as latex, resin, 

 etc. While these occur for the most part in the extra-xylem portions 

 of the plant, they may appear as vertical elements in the wood, as in 

 Carica (Papayacese), or horizontally in the rays where they serve as 

 connections between the tubes of the cortex and those of the pith, as 

 in representatives of the Apocynaceae, Asclepiadese (?), Euphorbiacese, 

 Lobeliaceas, and Moraceae. The writer has found the presence of these 

 tubes in the wood rays of Brosimum (Moraceae) to be a valuable diag- 

 nostic character. Trecul (9) noted connective laticiferous tubes in the 

 rays of certain species of Euphorbia, Dorstenia, Lobelia, Tupa, Iso- 

 toma, Centropogon, Siphocampylus, and Beaumontia. 



Following is a brief synopsis of the various families of the dicoty- 

 ledons in which intercellular canals in the wood have been observed by 

 the writer or reported by others. The lists are as complete as the writer 

 can make them at present, but undoubtedly are capable of considerable 

 extension. The writer is indebted to Prof. I. W. Bailey, of the Bussey 

 Institution, for specimens of several of the species listed. 



