Phytogeographical Excursion in the British Isles. 271 
THE INTERNATIONAL PHYTOGEOGRAPHICAL 
EXCURSION IN THE BRITISH ISLES. 
I. The Inception of the Excursion. 
HE study of Phytogeography, from the very nature of the 
1 material with which it deals, demands a comparison of the 
flora and vegetation of different parts of the earth’s surface, and 
this is equally true of the floristic side, which is concerned with the 
distribution of species, and of the ecological side, which 
deals with the distribution of vegetatation, i.e., of plant-com¬ 
munities. Floristic botanists, owing to limitations of time and 
money, largely depend for their material upon herbaria-collections 
of dried plants from different parts of the world. In times past at 
any rate, many of the most eminent are said to have been almost 
unable to recognise living plants of species with which they were 
perfectly familiar in the herbarium, and it is notorious that by far 
the larger number of diagnoses of species are founded upon dried 
material alone. The divorce of the study of systematic botany 
from the study of plants as living organisms thus resulting, has 
very often been recognised and deplored. There is no need to 
labour the point again. The formation and study of herbaria are 
of course essential, and even apart from limitations of time and 
space, could never be wholly replaced by personal investigation in 
the field and laboratory. But it will be very generally admitted 
that the systematic botanist who spends little time in the field and 
never becomes thoroughly acquainted with living plants at first 
hand must necessarily be ill-equipped for his task. Of course 
very many systematists actively pursue, and always have actively 
pursued, their studies in the field, both in their own and in other 
countries. Important light is always thrown on the flora of a 
country by the study of the floras of the neighbouring countries, 
and indeed such study is essential to its proper understanding. 
Hitherto no mechanism has existed for the investigation of a flora 
by botanists from neighbouring countries in company with native 
botanists. Isolated visits to this end have no doubt been frequent, 
but carefully organised international excursions have hardly 
existed, except indeed incidentally in connexion with international 
congresses. In recent years the most important of these have been 
organised in connexion with the International Congress of 
