Roots of Some Rosaceous Genera. 63 



beautiful golden pigment, while the cell walls were not 

 pigmented. I have not studied sections of the root of this 

 species during different times of the year. In some species a 

 difference can be traced in the amount of pigment according to 

 the season of the year in which the sections are studied. As 

 examples of this fact I would quote the conditions observed in 

 Agrivionia paj-viflora and Spima Filipe^idula. In the former 

 species, sections taken from roots collected in September 

 showed very little pigment in the cell walls or cavities of the 

 uniseriate layers, sections from those collected in December 

 contained no pigment, while sections from roots collected in 

 July had pigment alike in the cell walls and in the cell cavities 

 of this layer. In the latter species, sections taken from roots 

 collected in December and April showed cells almost lacking 

 pigment in the cell walls and cell cavities, while sections taken 

 from roots collected in July showed pigment in the cell walls 

 of all the cells, as well as pigment in the cell cavities of the 

 uniseriate layers. While I have attempted to determine the 

 chemical nature of this pigment, I have not as yet obtained 

 sufficiently definite results to draw conclusions. 



(/) Comparison of Root and Shoot.— ^ot very many obser- 

 vations have been made along this line, but I will note the 

 following : Intercellular spaces have been observed in the cork 

 region of the rhizome of Genm album, Rosa, Alchemilla 

 pyrenaica and Rubus villosus stem. In stems of Pynis Mains 

 and P. communis there are no intercellular spaces. In general 

 it may be said that in those species studied, the cork region of 

 the stem was more strongly suberized than that of the root as 

 was shown by the use of the cork tests. 



{g) Evidence as to the Relative Evolutionary Position of the 

 Rosaceous Groups. — In treating the RosacecB as an order Dr. 

 Macfarlane informs me that he regards the only workable 

 scheme of evolutionary relationship in this order to be one that 

 follows closely the following lines : Starting with the Poten- 

 tUlecB as the most primitive group, we pass by tolerably direct 



