118 DOTTINGS ON THE ROADSIDE. [Chap. VIII.-B.S. 
cult to conjure up by pen or pencil tire flora of a 
country as it was in times gone by, as it would be 
that of any former geological period. By not taking 
these changes into account, those who endeavour to 
give us vivid pictures of the past—historians, histo¬ 
rical painters, and romance writers—often fall into the 
error of using, as a background for ancient historical 
events, the country in which they happened in its 
modern aspect, an anachronism as painful to a botanist 
as a wrong note is to a musical ear. In a well-known 
print, “Joseph Sold by his Brethren,” the artist has 
carefully represented the date-palm and other features 
of the desert, but he has committed the blunder of 
introducing the American cactus, which did not reach 
Syria till several thousand years after the time of 
Joseph’s death. Some time ago, I saw in a Euro¬ 
pean capital a play founded upon some incident of 
early Boman history. The stage accessories had been 
executed with pre-Bafaelitic accuracy. There was the 
Boman landscape in all its beauty; the melancholy 
cypress, and the stone-pine of Italy, the outline of 
which Pliny so happily compares with the smoke of 
, Vesuvius as it issued from the crater 1800 years ago, 
and still issues in our year of grace, but there was 
also, unfortunately, the American aloe (Agave), which 
at present forms such a prominent feature of many a 
South European landscape, but was confined to the 
New World before the days of Columbus. 
Amongst plants a silent struggle for the possession 
of the soil is constantly going on. Even when no 
foreign elements are introduced into the flora of a 
