But if he confine his attention to one class within one
country, he will soon make up his mind how to rank most of the
doubtful forms. His general tendency will be to make many species, for
he will become impressed, just like the pigeon or poultry-fancier
before alluded to, with the amount of difference in the forms which he
is continually studying; and he has little general knowledge of
analogical variation in other groups and in other countries, by which
to correct his first impressions. As he extends the range of his
observations, he will meet with more cases of difficulty; for he will
encounter a greater number of closely-allied forms. But if his
observations be widely extended, he will in the end generally be
enabled to make up his own mind which to call varieties and which
species; but he will succeed in this at the expense of admitting much
variation,--and the truth of this admission will often be disputed by
other naturalists. When, moreover, he comes to study allied forms
brought from countries not now continuous, in which case he can hardly
hope to find the intermediate links between his doubtful forms, he
will have to trust almost entirely to analogy, and his difficulties
will rise to a climax.
Certainly no clear line of demarcation has as yet been drawn between
species and sub-species--that is, the forms which in the opinion of
some naturalists come very near to, but do not quite arrive at the
rank of species; or, again, between sub-species and well-marked
varieties, or between lesser varieties and individual differences.
Pages:
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78