Remarks on the Floristic Results. 53 
VI—Some REMARKS ON THE FLORISTIC RESULTS OF 
THE EXCURSION. 
Owinc to the excellent manner in which Mr. Tansley had 
arranged the conditions for preparing herbarium plants during our 
excursion, it was possible, in spite of the short time, to make 
ample collections at all points of our extensive trip. To me it was 
of special interest to get as many British plants as possible, as I 
was anxious to compare them with more northern and with Danish 
plants. I devoted special attention to the forms of the more 
critical species, and have brought home a large number of such 
plants. My leading idea in so doing is that a study of the geogra- 
phical distribution of the “ elementary” species or forms may be 
of value with regard to the interpretation of the immigration of the 
postglacial flora and the paths which this may have followed. As 
illustrations of my point of view the two races of Helianthemum 
nummularium, viz., var. hirsutum and var. tomentosum may be 
cited. In Denmark we have the former almost alone, while in the 
British Isles only the latter is found ; this means that one variety 
has travelled in a western direction, the other in a northern, 
since both occur in Central Europe, Very much the same is the 
case with the two varieties of Lamium galeobdolon, of which var. 
