26 ACCLIMATATION. 
“The constitution of such plants does not appear to be 
more capable of resisting an unfavourable climate than that of 
their forefathers. It is perfectly true that many so-called 
greenhouse plants are now known to be hardy; but such 
species have not increased their power of resisting our climate; 
they never were tender;” and it is added, “If no good evidence 
can be produced of plants having become acclimated by re- 
peated sowings of their seed, the facts on the other side 
are numerous and conclusive. The Peruvian annual called 
Marvel of Peru, or Mirabilis, the common Indian cress or 
Tropeolum, the scarlet running kidney bean, the tomato, the 
mignonette, an African plant, the Palma Christi, or Azcinus, 
all natives of hot climates, have been annually raised from 
seeds ripened in this country, some of them for two hundred 
generations ; yet have in no appreciable degree acquired 
hardiness, but the earliest frost destroys them now as formerly. 
“ Potatoes, long as they have been cultivated from seeds, 
are in no degree more hardy than those which are now 
brought to us from Peru and Mexico; indeed, some garden 
potatoes, imported in 1846 from Lima, and planted in Novem- 
ber, stood the severity of the succeeding winter, when the 
thermometer fell to 3° Fahr., rather better than the English 
varieties which had been obtained from repeated seed-sowing 
during a century.” 
It is well known to market-gardeners that the earliest 
varieties of the potato grown in the best climate of South 
Britain when imported into the North become degenerate, and 
later in the open ground, and this most readily when grown 
at a high altitude. The same is observable respecting pota- 
toes grown in hot-beds; the first crops they produce are 
earlier than if the parent roots had been grown in the open 
ground, and a climatic change is effected, although it does not 
enable the potato to resist frost. 
A similar change of lateness takes place in the growth of 
the early varieties of garden pease. The first generation of 
the early frame pea from seeds grown in Essex, when raised 
in the north of Scotland will yield a variety that cannot be 
