242 ROYAL SOCIETY OF CANADA 



to be composed of radially elongated cells disposed in two or more series, 

 but outwardly becoming abruptly shortened and passing into cork 

 toward the outer face (fig. 6, o.f.) The tissue immediately abutting 

 upon the rays is that of the general parenchyma structure, and the draw- 

 ing (fig 6) gives one more example oî the very irregular deveLopment it 

 presents, as well as the extent and character of the intercellular spaces. 

 In the longitudinal section, the rays are generally several cells high (fig. 

 3, mr.), and in all cases they are found to extend from the central cavity 

 through the entire thickness of the parenchyma layer to the cork, with 

 which their structure becomes blended. 



On the outer face of the parenchyma tissue, there is a well defined 

 layer of cork, the two being united into one structure throughout, with 

 no evidence at any point, of an absciss layer. Nor is there any well de- 

 fined evidenc3 of a phellogen layer which evidently disappeared com- 

 pletely' at the moment of full maturity. From this description it is 

 obvious that the innermost layer of structure is composite, and that it 

 consists on its inner face of the residue of parenchyma tissue of which 



Fig 5. x 250. 



the entire growth must have been <3omposed in the first instance, while 

 upon its outer face it consists of cork, the latter constituting approxi- 

 mately about one-third of the entire layer and representing the last pro- 

 duct in the activity of the growing parts. 



The cork presents, in the main, the features usually characteristic 

 of such a tissue, deviating in detail with respect to (1) the somewhat 

 unusual thickness of the cell walls, and (2) the presence of very abun- 

 dant cell contents which persist throughout the entire structure (figs. 2 

 and 7) and do not disappear until the outermost layers have been 

 brought under the influence of weathering and the bleaching process is 

 developed. An inspection of the various layers of cork shows that each 

 is composed of about six to eight cells with very great constancy. The 

 various layers are separated by an absciss layer of one or rarely of two 

 cells, the walls of which are very thin and easily ruptured, the cell itself 

 being about twice the radial diameter of the adjacent and unmodified 

 cork cells. The process of desiccation incident to full maturity, appears 



