n a letter to Sir Joseph
Banks, published in the Philosophical Transactions for 1813. It appears
that one Seth Wright, the proprietor of a farm on the banks of the
Charles River, in Massachusetts, possessed a flock of fifteen ewes and a
ram of the ordinary kind. In the year 1791, one of the ewes presented
her owner with a male lamb, differing, for no assignable reason, from
its parents by a proportionally long body and short bandy legs, whence
it was unable to emulate its relatives in those sportive leaps over the
neighbours' fences, in which they were in the habit of indulging, much
to the good farmer's vexation.

The second case is that detailed by a no less unexceptionable authority
than Reaumur in his "Art de faire eclore les Poulets." A Maltese couple,
named Kelleia, whose hands and feet were constructed upon the ordinary
human model, had born to them a son, Gratio, who possessed six perfectly
moveable fingers on each hand and six toes, not quite so well formed, on
each foot. No cause could be assigned for the appearance of this unusual
variety of the human species.

Two circumstances are well worthy of remark in both these cases. In
each, the variety appears to have arisen in full force, and, as it were,
_per saltum_; a wide and definite difference appearing, at once, between
the Ancon ram and the ordinary sheep; between the six-fingered and
six-toed Gratio Kelleia and ordinary men. In neither case is it possible
to point out any obvious reason for the appearance of the variety.
Doubtless there were determining causes for these as for all other
phaenomena; but they do not appear, and we can be tolerably certain that
what are ordinarily understood as changes in physical conditions, as in
climate, in food, or the like, did not take place and had nothing to do
with the matter. It was no case of what is commonly called adaptation to
circumstances; but, to use a conveniently erroneous phrase, the
variations arose spontaneously. The fruitless search after final causes
leads their pursuers a long way; but even those hardy teleologists, who
are ready to break through all the laws of physics in chase of their
favourite will-o'-the-wisp, may be puzzled to discover what purpose
could be attained by the stunted legs of Seth Wright's ram or the
hexadactyle members of Gratio Kelleia.

Varieties then arise we know not why; and it is more than probable that
the majority of varieties have arisen in this "spontaneous" manner,
th