exists a little
plant with a fusiform root, smooth glaucous leaves, flowers similar to
wild mustard and of a saline taste. It is called by botanists,
_Brassica oleracea_. By cultivation there have been obtained from this
insignificant and apparently useless plant--

1st, all borecoles or kails, 12 varieties or more.
2d, all cabbages having heart.
3d, the various kinds of Savoy cabbages.
4th, Brussels sprouts.
5th, all the broccolis and cauliflowers which do not heart.
6th, the rape plant.
7th, the ruta baga or Swedish turnip.
8th, yellow and white turnips.
9th, hybrid turnips.
10th, kohl rabbi.

Similar examples are numerous among our common useful plants, and
among flowers the dahlia and verbena furnish an illustration of
countless varieties, embracing numberless hues and combinations of
color, from purest white through nearly all the tints of the rainbow
to almost black, of divers hights too, and habits of growth, springing
up under the hand of cultivation in a few years from plants which at
first yielded only a comparatively unattractive and self-colored
flower. In brief, it may be said, that nearly or quite all the
choicest productions both of our kitchen and flower gardens are due to
variations induced by cultivation in a course of years from plants
which in their natural condition would scarcely attract a passing
glance.

We cannot say what might have been the original type of many of our
domestic animals, for the inquiry would carry us beyond any record of
history or tradition regarding it, but few doubt that all our
varieties of the horse, the ox, the sheep and the dog, sprang each
originally from a single type, and that the countless variations are
due to causes connected with their domestication. Of those reclaimed
within the period of memory may be named the turkey. This was unknown
to the inhabitants of the old continent until discovered here in a
wild state. Since then, having been domesticated and widely
disseminated, it now offers varieties of wide departure from the
original type, and which have been nurtured into self-sustaining
breeds, distinguished from each other by the possession of peculiar
characteristics.

Among what are usually reckoned the more active causes of variation
may be named climate, food and habit.

Animals in cold climates are provided with a thicker covering of hair
than in warmer ones. Indeed, it is said that in some of th