; HISTORY OF PLANTS. 879 | 
That prolific hybrids are not a very extraordinary 
phenomenon in the vegetable kingdom, we had an 
opportunity of observing before, (§ 298). We often 
see them produced in our gardens, and cannot 
therefore deny the possibility of their generation in 
open air. But nature has wisely guarded against 
too easy a commixtion of such plants in their un- 
cultivated, free state. For we often find plants of the 
ereatest likeness in partsof the globe very distant from 
- each other, andat very different periods, and in different 
places in blossom. Plants of great likeness and simi- 
larity only can be mixed and produce a hybrid off- 
spring. Hence such a commixture never happens 
where only few species of the same genus grow in 
one climate. One instance will sufficiently explain 
this: three species of Scrophularia grow wild about 
Berlin, to wit, Scrophularia verna, nodosa and aqua- 
tica. ‘Yhe first grows in villages, about hedges, and 
blossoms in spring. ‘The second grows in moist 
meadow ground, near ditches, and blossoms a month 
later. ‘The last grows in rivers, rivulets, marshes, 
and ponds, and flowers more than four weeks later 
than the second. Other species of the same genus, 
and very like those three, grow in Italy, Siberia, in 
the East, North America, &c. In all those, no hy- 
prids can be formed in their natural state. But 
were we to place in a botanical garden all the species, 
foreign as well as indigenous, in on espot, no wonder 
if the very different climate and soil, which would 
probably disagree with many species, would bring 
the flowers out sooner or later than natural, and that » 
swarms of insects, flying from species to species, 
might, 
