Roots of Some Rosaceous Gcjiej-a. 55 



walls, between which intercellular spaces are formed, together 

 with occasional compact layers of cells with a suberized zone." 



The points presented in this paper will be given under the 

 following headings : 



{a) Intercellular spaces and annular arrangement of cell 

 layers. 



{b) Suberization of the periderm. 



(r) Presence of nuclei in cells of the cork region. 



(^) Starch in the cork region. 



{e) Pigment of the cork region. 



(/") Comparison of root and shoot. 



(^) Evidence as to the relative evolutionary position of the 

 Rosaceous groups. 



{h) Summary of results. 



{a) Intercellular Spaces and Annular Arrangement of Cell 

 Layers. — ^The following groups of the Rosacea have been 

 studied, with a view to solving the problem of the presence or 

 absence of intercellular spaces, with the appended results : 



Group Potentillece. — Ten species of this group have been 

 studied, viz.: P. tiort>egica, P. chrysantha, P. alpcstris, P. geoidcSy 

 Geuin atrosanguineum, G. album, G. 7iutans, G. triforum, Fra- 

 garia indica and Waldsteinia geoidcs. All the above species 

 of this group have been observed to contain intercellular 

 spaces, which are quadrangular in shape. A noticeable 

 character of the cork region of this group is the annular 

 arrangement of the cell layers. These may be arranged 

 according to three types : First, alternating layers of cells of 

 different sizes as in Geuin albiim ; second, alternating uniseriate 

 layers of cells whose cavities contain pigment, and of cells 

 devoid of pigment contents, as in Waldsteinia geoides ; third, 

 uniseriate layers of flattened compact cells, with deeply 

 pigmented cell walls whose cell cavities contain a brown 

 pigment, alternating with less compact multiseriate layers 

 which contain no pigment within the cell cavities, but which 

 may sometimes have their walls pigmented, especially in the 



