INTRODUCTORY ESSAY. IX 
port the views of those who regard species as permanent. A further acquaintance 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 ccrealia, such as the Cabbage 
and its numerous progeny, and the varieties of wall-fruit, show when neglected no disposition to 
assume the characters of the wild states of these plants;* they certainly degenerate, and even die if 
Nature does not supply the conditions which man (by anticipation of her operations, or otherwise) has 
provided ; they become stunted, hard, and woody, and resemble their wild progenitors in so far as all 
stunted plants resemble wild plants of similar habit ; but this is not a reversion to the original type, 
for most of these cultivated races are not merely luxuriant forms of the wild parent. In neglected 
fields and gardens we see plants of Scotch Kale, Brussels Sprouts, or Kohl-rabi, to be all as unlike 
their common parent, the wild Brassica oleracea, as they are unlike one another ; so, too, most of our 
finer kinds of apples, if grown from seed, degenerate and become crabs, but in so doing they become 
crab states of the varieties to which they belong, and do not revert to the original wild Crab-apple. 
And the same is true to a great extent of cultivated Roses, of many varieties of trees, of the Rasp- 
berry, Strawberry, and indeed of most garden plants. It has also been held, that by imitating the 
conditions under which the wild state of a cultivated variety grows, we may induce that variety to 
revert to its original state ; but, except in the false sense of reversion above explained, I doubt if this 
is supported by evidence. Cabbages grown by the seaside are not more like wild Cabbages than 
those grown elsewhere, and if cultivated states disseminate themselves along the coast, they there 
retain their cultivated form. This is however a subject which would fill a volume with most instruc- 
tive matter for reflection, and which receives a hundredfold more illustration from the Animal than 
from the Vegetable Kingdom. I can here only indicate its bearing on the doctrine of variation, 
as evidence that Nature operates upon mutable forms by allowing great variation, and displaying 
little tendency to reversion. t With this law the suggestive observation of M. Vilmorin well accords, 
that when once the constitution of a plant is so broken that variation is induced, it is easy to multi- 
ply the varieties in succeeding generations. 
It may be objected to this line of argument that our cultivated plants are, as regards their 
constitution, in an artificial condition, and are, if unaided, incapable of self- perpetuation ; but an arti- 
ficially induced condition of constitution is not necessarily a diseased or unnatural one, and, so far as 
our cultivated plants are concerned, all we do is to place them under conditions which Nature does 
not provide at the same particular place and time. That Nature might supply the conditions at other 
places and times may be inferred from the fact that the plant is found to be provided with the means 
of availing itself of them when provided, while at the same time it retains all its functions, not only 
unimpaired, but in many cases in a more highly developed state. We have no reason to suppose 
that we have violated Nature's laws in producing a new variety of wheat,— we may have only anti- 
cipated them ; nor is its constitution impaired because it cannot, unaided, perpetuate its race j it is 
in as sound and unbroken health and vigour during its life as any wild variety is, but its offspring 
* Hence the great and acknowledged difficulty of determining the wild parent species of most of our cultivated 
fruits, cerealia, etc., and in fact of almost every member of our Flora Cibaria. This would not be so were there 
any disposition in the neglected cultivated raced to revert to the wild form. 
f It is not meant by this that any character of a species which may be lost in its variety never reappears in 
the descendants of the latter, for some occasionally do so in great force ; what is meant is, that the newly acquired 
5 of the variety are aever 90 entirely obliterated that it has no longer a claim to be considered a variety. 
