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J. D. Hooker, Introductory Essay to the Flora of Tasmania. 11 
that the prevalent opinion is that there is a strong tendency in 
cultivated, and indeed in all varieties, to revert to the type from 
which they departed; and I have myself quoted this opinion, 
without questioning its accuracy,* as tending to support the views 
of those who regard species as permanent. A further acquaint- 
ance with the results of gardening operations leads me now to 
doubt the’ existence of this centripetal force in varieties, or at 
least to believe that in the phrase ‘reversion to the wild type,” 
many very different phenomena are included, In the first place, 
the majority of cultivated vegetables and cerealia, such as the 
rime and its numerous progeny, and the varieties of wall- 
volume with most instructive matter for reflection, and which 
receives a hundredfold more illustration from the Animal than 
from the Vegetable Kingdom. I can here only indicate its bear- 
ing on the doctrine of variation, as evidence that Nature operates 
upon mutable forms by allowing great variation, and displaying 
