Origin of Species Variorum

→ this 1861 1866

whether they could do so 1869 1872

→ being apparently not 1861 1866

not being 1869 1872

→ we may infer as highly probable 1861 1866 1869 1872

I have very little doubt, 1859 1860

→ two-thirds 1860 1861 1866 1869 1872

two thirds of 1859

2,700 seeds, but the same number of protected heads produced not a single seed. Humble-bees alone visit red clover, as other bees cannot reach the nectar. It has been suggested that moths may

~~serve to~~

serve to

fertilise the clovers; but I doubt →this in the case of the red clover, from their weight →being apparently not sufficient to depress the

wing petals.

wing-petals.

Hence →we may infer as highly probable

that,

that

if the whole genus of humble-bees became extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great

measure

degree

on the number of field-mice, which destroy their combs and nests; and

Col.

Mr. H.

Newman, who has long attended to the habits of humble-bees, believes that "more than →two-thirds

them

of them

are thus destroyed all over England." Now the number of mice is largely dependent, as every one knows, on the number of cats; and

Col. Newman

Col.Newman

Mr. Newman

says, "Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the

numbe

number

r of

cats that destroy the mice." Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!

In the case of every species, many different checks, acting at different periods of life, and during different seasons or years, probably come into play; some one check or some few being generally the most

potent;

potent,

but all

concurring

will concur

concur

in determining the average number or even the existence of the species. In some cases it can be shown that widely-different checks act on the same species in different districts. When we look at the plants and bushes clothing an entangled bank, we are tempted to attribute their proportional numbers and