152 
BISET OR WILD ROCK-PIGEON. 
nerated all the various races and peculiar varieties, 
which, it is well known, when once produced, may 
he perpetuated for an indefinite period, by being 
kept separate from, and unmixed with, others ; or 
what, by those interested in such pursuits, is usual- 
ly termed “ breeding in and in.” Such also, we may 
add, is the opinion of the most eminent naturalists, 
as to their origin, and it is strongly insisted on by 
M. Temminck in his valuable woik,_ the Histoire 
Generale Naturelle des Pigeons. Indeed, the fact, 
that all the varieties, however much they may differ 
in colour, size, or other particulars, if permitted, 
breed freely and indiscriminately with each other, 
and produce a progeny equally prolific, is another 
and a convincing proof of their common and self- 
same origin ; for it is one of those universal laws of 
nature, extending even to plants, and one which, if 
once set aside or not enforced, would plunge all ani- 
mated matter into indescribable confusion, that the 
offspring produced by the intercourse of diS'erent, 
that is, distinct species, is incapable of further in- 
crease. That such an intercourse may he effected, 
is well known to all ; but it is generally under pe- 
culiar or artificial circumstances, and rarely when the 
animals, birds, or whatever they may be, are in their 
natural state, and in a condition to make their own 
election. It is seen in the crosses obtained, in a 
state of confinement, between the canary and gold- 
finch, linnet, &c. ; in the hybrids produced between 
different species of the Anatidse when domesticated, 
