176 
THE FLORIST’S JOURNAL. 
the same season ; but by what process the change is effected we 
cannot very well understand. We know, however, that in every 
case where a single flower is converted into a double one which 
maintains its character, the anthers of the single flower are 
always numerous in proportion to the degree of doubling that can 
be obtained; and therefore the analogy would lead us to con¬ 
clude that the production of petals is something intermediate 
between mere growth and the fertilizing of seeds. Therefore, 
the fair conclusion is, that this doubling is brought about by an 
intermediate treatment, arising from natural circumstances, from 
the efforts of the florist, or from the two jointly. Farther, the 
anthers are always diminished in proportion as the petals are 
increased; and sometimes the petals are so numerous that the 
parts of fructification are concealed, and their productive power 
is greatly diminished. Nature sometimes sports these double 
flowers; but it is doubtful whether any of these sportings will 
produce a permanent variety. 
The Dahlia is a good instance of this doubling by difference of 
climate and culture. All the Dahlias are originally from Mexico, 
that is, from the table-land, where the average temperature is 
considerably lower than it is on the slopes toward the sea, which 
have a tropical vegetation. In respect of variation of heat, 
Mexico is not a much more seasonal country than Britain ; but it 
is more seasonal in the alternations of rain and drought. In con¬ 
sequence of the first of these circumstances, many of the plants 
can bear any climate in the open air as long as the temperature is 
above freezing; and, in consequence, they are rather easil} 
varied by artificial treatment. In its native country, the Dahlia 
has a single row of petals, and the centre of the disc is filled up 
with parts of fructification. The stems, which are annual, just 
as they are with us, die down in the commencement of the dry 
season, just as they do with us when the frost first sets in ; and 
after the stems are gone, the tuberous roots remain inactive in 
the dry ground till the rains return. The season of their repose 
with us is the wet season ; and if we leave them in the ground 
their flowers degenerate ; but we get the better of this b) taking 
them up, and keeping them dry during the winter and the "seiy 
early spring. Our climate is thus more favouiable to the simple 
growth of a Dahlia than the climate of Mexico ; but it is not so 
favourable for bringing forward the parts of fructification, more 
