Roots of Some Rosaceous Genera. 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. 



(^) Suberization of the periderm. 



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



{d) Starch in the cork region. 



(^) Pigment of the cork region. 



(/) Comparison of root and shoot. 



{g) Evidence as to the relative evolutionary position of the 

 Rosaceous groups. 



(/if) Summary of results. 



{a) Intercellular Spaces and Annular Arrangement of Cell 

 Layers. — The following groups of the Rosacece have been 

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

 absence of intercellular spaces, with the appended results : 



Group Potcntillecc. — Ten species of this group have been 

 studied, viz.: P. non^egica, P. chrysantha, P. alpcstris, P. geouies, 

 Geum atrosanguiiicum, G. albuni, G. nutans, G. triflorum, Fra- 

 garia indica dcnA Waldsteinia gcoidcs. 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 Geum album ; 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 



