REVIEWS—ON THE ORIGIN OF SPECIES. 373 
many closely related species (z. e. species of the same genus) have been formed, 
many varieties or incipient species ought, as a general rule, to be now forming. 
Where many large trees grow, we expeet to find saplings, Where many species 
of a genus have been formed throuzh variation, circumstances have been favourable 
for variation; and hence we might expect that the circumstances would generally 
be still favourable to variation. On the other hand, if we look at each species as 
a special act of creation, there is no apparent reason why more varieties should 
occur in a group having many species, than in one having few. 
To test the truth of this anticipation [have arranged the plants of twelve 
countries, and the coleopterous insecis of two districts, into two nearly equal 
masses, the species of the larger genera on one side, and those of the smaller 
genera on the other side, and it has invariably proved to be the case that a larger 
proportion of the species en one side of the larger genera present varieties, 
than on the side of the smaller genera. Moreover, the specics of the large 
genera which present any varieties, invariably present a larger average number 
of varieties than do the species of the small genera. Both these results follow 
when another division is made, and when all the smaller genera, with from only 
one to four species, are absolutely excluded from the tables. These facts are 
of piain signification on the view that species are only strongly marked and 
permanent varieties; for wherever many species of the same genus have been 
formed, or where, if we may use the expression, the manufactory of species has 
been active, we ought generally to find the manufactory still in action, more 
especially as we have every reason to believe the process of manufacturing new 
species to be a slow one. And this certainly is the case, if varieties be looked at 
as incipient species; for my tables clearly show asa veneral rule that, wherever 
many species of a genus have been formed, the species of that genus present a 
nutaber of varieties, that is, of incipient species, beyond theaverage. It is nob 
that all large genera are now varying much, and are thusinereasing in the number 
of their species, or that no small genera are now varying and inereasing; for if 
this had been so, it would have been fatal to my theory ; inasmuch as geology 
plainly tells us that small genera have in the lapse of time often greatly increased 
in size; and that large genera have often come to their maxima, declined and 
disappeared. All that we want to show is, that where many species of a genus 
have been formed, on an average many are still forming ; and this holds good. 
With regard to the deductions contained in this quotation, as bear- 
ing on the origin of actual species, two things have to be observed: 
first, that many of the so-called species of these large genera may not 
be, and in many cases decidedly are not, true species; and secondly, 
as already observed in the case of the dog, &c., many leading varieties | 
in these genera, may be varieties of original creation, or sub-spocies if 
we choose to call them so; and thus, a larger amount of material for 
variation being provided in the one case than in the other, a more 
extended variation in the former will follow as a natural consequence. 
