are
characterized as varieties in Mr. Wollaston's admirable work, but
which it cannot be doubted would be ranked as distinct species by many
entomologists. Even Ireland has a few animals, now generally regarded
as varieties, but which have been ranked as species by some zoologists.
Several most experienced ornithologists consider our British red grouse
as only a strongly-marked race of a Norwegian species, whereas the
greater number rank it as an undoubted species peculiar to Great
Britain. A wide distance between the homes of two doubtful forms leads
many naturalists to rank both as distinct species; but what distance, it
has been well asked, will suffice? if that between America and Europe
is ample, will that between the Continent and the Azores, or Madeira, or
the Canaries, or Ireland, be sufficient? It must be admitted that many
forms, considered by highly-competent judges as varieties, have so
perfectly the character of species that they are ranked by other
highly-competent judges as good and true species. But to discuss whether
they are rightly called species or varieties, before any definition of
these terms has been generally accepted, is vainly to beat the air.

Many of the cases of strongly-marked varieties or doubtful species well
deserve consideration; for several interesting lines of argument, from
geographical distribution, analogical variation, hybridism, etc., have
been brought to bear on the attempt to determine their rank. I will here
give only a single instance,--the well-known one of the primrose and
cowslip, or Primula veris and elatior. These plants differ considerably
in appearance; they have a different flavour and emit a different
odour; they flower at slightly different periods; they grow in somewhat
different stations; they ascend mountains to different heights; they
have different geographical ranges; and lastly, according to very
numerous experiments made during several years by that most careful
observer Gartner, they can be crossed only with much difficulty.
We could hardly wish for better evidence of the two forms being
specifically distinct. On the other hand, they are united by many
intermediate links, and it is very doubtful whether these links are
hybrids; and there is, as it seems to me, an overwhelming amount of
experimental evidence, showing that they descend from common parents,
and consequently must be ranked as varieties.

Close investigation, in most cases, will bring naturali