180 f. W. C. Areschoug. 



very unaccountable, that in the same genus, two such different procedures for 

 the 01 igin of forms could exist. This coritradiction is explained, however, when 

 the intermediate forms are considered, as here laid down, and which I have be- 

 fore explained in detail. 



It is only the groups of the genus, that have a large geographical exten- 

 sion on the Scandinavian penihsula, in which such intermediate forms are to 

 be found. They are particularly frequent among the corylifolians, which also 

 probably have given origin to ä great luunber of the European brarnbles (pages 

 108 — 109). The Suberecti also produce not a tew intermediate forms. R. 

 fruticpsus developes intermediate forms that approach R. sulcatus (page lfiO), 

 and from R. suberectus forms arise that resemble R. fissus, or even R. sul- 

 catus (page 167). R. insularis has also in the northwest of Skåne, developed 

 forms that connect this species with R. polyanthemos (page 139). R. Are- 

 sehougii which was developed from R. saxatilis, is a remarkable intermediate 

 form between that species and R. caesius: Such forms arise, most frequently, 

 on the borders of the geographical area of that species which they resemble 

 (pages 109 — 110). They are very often sterile and thus resemble hybrids 

 (page 110). 



It is hardly necessary to remark, that this examination of intermediate 

 forms does not deny the existence of transitional forms. The great changes 

 in the plant cannot be completely carried out at once. They take place step 

 by step, and only one step can be taken at a time. R. glandulosus e. g. 

 did not produce R. horridus at once, but it developed R. pallidus, and from 

 that species a rose R. hor ii dus. 



9. The same species or variety can have ar/sen on several different sppts, 

 ir/llim its present geographical area (page 129). 



This being the case, it has the effect, that a species or form. in different 

 localitieß, is seldom exactly alike. R. pallidus in Swéden, does not quite agree 

 with the same species growing in the noith west of Germany (page 112), and 

 K. polyanthemos growing in the northwest of Skåne, differs, in some points, 

 from tlie same species growing on the Jutlandic peninsula (page 138); 



