ch organised matter is used in building
up some one part, other parts are starved and become reduced. Several
authors, especially botanists, believe in this law; others reject it. As
far as I can judge, it occasionally holds good; but its importance has
probably been exaggerated. It is scarcely possible to distinguish between
the supposed effects of such compensation of growth, and the effects of
long-continued selection, which {343} may at the same time lead to the
augmentation of one part and the diminution of another. There can be no
doubt that an organ may be greatly increased without any corresponding
diminution in the adjoining parts. To recur to our former illustration of
the Irish elk, it may be asked what part has suffered in consequence of the
immense development of the horns?

It has already been observed that the struggle for existence does not bear
hard on our domesticated productions; consequently the principle of economy
of growth will seldom affect them, and we ought not to expect to find
frequent evidence of compensation. We have, however, some such cases.
Moquin-Tandon describes a monstrous bean,[849] in which the stipules were
enormously developed, and the leaflets apparently in consequence completely
aborted; this case is interesting, as it represents the natural condition
of _Lathyrus aphaca_, with its stipules of great size, and its leaves
reduced to mere threads, which act as tendrils. De Candolle[850] has
remarked that the varieties of _Raphanus sativus_ which have small roots
yield numerous seed, valuable from containing oil, whilst those with large
roots are not productive in this latter respect; and so it is with
_Brassica asperifolia_. The varieties of the potato which produce tubers
very early in the season rarely bear flowers; but Andrew Knight,[851] by
checking the growth of the tubers, forced the plants to flower. The
varieties of _Cucurbita pepo_ which produce large fruit yield, according to
Naudin, few in number; whilst those producing small fruit yield a vast
number. Lastly, I have endeavoured to show in the eighteenth chapter that
with many cultivated plants unnatural treatment checks the full and proper
action of the reproductive organs, and they are thus rendered more or less
sterile; consequently, in the way of compensation, the fruit becomes
greatly enlarged, and, in double flowers, the petals are greatly increased
in number.

With animals, it has been found difficult to produce c