Distribution of the Flora in the A Ipine Zone. 43 
The results obtained by comparing adjacent areas, each one 
square metre in extent, from one and the same meadow, are even 
more surprising. In a sub-alpine meadow at an altitude of 1,200 
metres in the valley of the Ormonts (Alpes Vaudoises), where the 
species of 52 different square metres, each showing an average of 25 
to 30 species, were enumerated, the proportion of species common to 
two adjacent square metres generally varied between 60 and 75%. 
Thus on two square metres, A and B, peopled by 38 species, only 
25, or 66% were common to A and B. 
The dominant conclusion which emerges from the facts given 
above, is the infinite diversity of the alpine flora, and of the associations 
which constitute it, a diversity so great that probably no two square 
metres of vegetation in the whole chain of the Alps, possess exactly 
the same floristic composition. 
This diversity, which seems at first to escape all rule, really 
presents elements of regularity, which we have now to establish. 
III. 
Among the species which make up a plant covering, some are 
frequent, others less so, others again are very infrequent. These 
different degrees of frequency may be expressed by the four terms, 
rare, somewhat rare, somewhat common and common. These terms, 
as they are generally applied in the floras, are partly subjective, 
according to the degree to which the country to which they are 
applied has been explored, and to the judgment of the individual 
botanist who uses them. 
It is however possible to give such terms a purely objective 
value. If an area be divided into four equal and comparable 
portions, those species found in only one may be called rare, those 
found in two, somewhat rare, those found in three, somewhat 
common, and those found in all four, common. Using this principle, 
all degrees of frequency that may be desired can be determined by 
increasing the number of divisions of the given area. 
This method has been carried out for the 370 species collected 
on the 10 alpine meadows mentioned above, and for the 240 species 
noted on 12 localities of the pastures on the highest zone of the 
southern Jura. 
For the former we obtain the following degrees of frequency 
expressed in percentages :— 
