imals, besides children, to the belief that they can sting. The curious
attitude assumed by sphinx caterpillars is probably a safeguard, as well as
the blood-red tentacles which can suddenly be thrown out from the neck by
the caterpillars of all the true swallow-tailed butterflies."

But, because many different kinds of animals can elude the observation or
defy the attack of enemies in a great variety of ways, it by no means
follows that there are any similar number and variety of ways for attaining
vegetable food in a country where all such food, other than the lofty
branches of trees, has been for a time destroyed. In such a country we have
a number of vegetable-feeding Ungulates, all of which present minute
variations as to the length of the neck. If, as Mr. Darwin contends, the
natural selection of these favourable variations has alone lengthened the
neck of the giraffe by preserving it during droughts; similar variations,
in similarly-feeding forms, at the same times, ought similarly to have been
preserved and so lengthened the neck of some other Ungulates by similarly
preserving them during the same droughts.

(2.) It may be also objected, that the power of reaching upwards, acquired
by the lengthening of the neck and legs, must have necessitated a
considerable increase in the entire size and mass of the body (larger bones
requiring stronger and more voluminous muscles and tendons, and these again
necessitating larger nerves, more capacious blood-vessels, &c.), and it is
very problematical whether the disadvantages thence arising would not, in
times of scarcity, more than counterbalance the advantages.

For a considerable increase in the supply of food would be requisite on
account of this increase in size and mass, while at the same time there
would be a certain decrease in strength; for, as Mr. Herbert Spencer {28}
says,[23] "It is demonstrable that the excess of absorbed over expended
nutriment must, other things equal, become less as the size of an animal
becomes greater. In similarly-shaped bodies, the masses vary as the cubes
of the dimensions; whereas the strengths vary as the squares of the
dimensions.".... "Supposing a creature which a year ago was one foot high,
has now become two feet high, while it is unchanged in proportions and
structure--what are the necessary concomitant changes that have taken place
in it? It is eight times as heavy; that is to say, it has to resist eight
times the strain which