THK GENUS ROSA 257 



by observing the break of the glaucous and the green micro- 

 genes of certain AfzeliancE into their smooth and hairy forms, 

 he followed its occurrence throughout that group, and in the 

 end proved its universality in the rose sections. With the 

 huge mass of material at his command, and attacking the 

 matter purely from the standpoint of the systematist, he proved 

 that there v^ere 31 species-types and fully characterised them, 

 utilising, in addition to the features employed by me, the 

 forms and relationships of the leaflets on the flowering sprigs 

 as the basis of his scheme. On this foundation he constructed 

 a tabular synopsis of the sections, species-types, microgenes 

 and varieties ; but in this many blank spaces exist. 



All of this he carried out without the slightest inkling of its 

 genetic import ; nevertheless his table can be used as a kind 

 of Mendeleeft's Periodic Classification to predict the existence 

 of roses as yet undiscovered. Prior to this, however, on the 

 evidence of my own work, I had outlined and lectured on a 

 similar scheme evolved, after prolonged study, from my seven- 

 teen or more species-types. Moreover, I had employed my own 

 arrangement with conspicuous success to predict the occurrence 

 of a great number of forms (chiefly Agrestes) allied to 

 Rosa blondaeana and R. sclerophylla which I afterwards dis- 

 covered in South Durham and North Yorks where that group 

 abounds. 



The similarity of the tables developed by both Almquist 

 and myself to that drawn up by Mendeleeff to illustrate the 

 Periodic Law in classifying the chemical elements cannot be 

 too strongly emphasised. Almost to the most minute detail 

 they agree ; we have the vertical groups of the chemist agreeing 

 with my section-species, the horizontal series or periods w^ith 

 our species-types. Furthermore, if we allow for the division 

 of the six members of the Canince into three pairs of more 

 nearly related section-species, we have an immediate parallel 

 to the divergence of the groups in IMendeleefFs table into two 

 subgroups. For instance, the relationship between the 

 EucaniiicB and Afzeliance is much the same as that between 



