434 
DARWINISM 
CHAP. 
exclusive and unmodified action are nowhere to he found in 
nature. It may be allowed to rank as one of those “laws of 
growth,” of which so many have now been indicated, and 
which were always recognised by Darwin as underlying all 
variation ; but unless we bear in mind that its action must 
always be subordinated to natural selection, and that it is 
continually checked, or diverted, or even reversed by the 
necessity of adaptation to the environment, we shall be liable 
to fall into such glaring errors as the imputing to “ ebbing 
vitality ” alone such a widespread phenomenon as the occur¬ 
rence of spines and thorns, while ignoring altogether the 
influence of the organic environment in their production. 1 
The sketch now given of the chief attempts that have been 
made to prove that either the direct action of the environment 
or certain fundamental laws of variation are independent causes 
of modification of species, shows us that their authors have, 
in every case, failed to establish their contention. Any direct 
action of the environment, or any characters acquired by use 
or disuse, can have no effect whatever upon the race unless 
they are inherited; and that they are inherited in any case, 
1 The general arguments and objections here set forth will apply with equal 
force to Professor G. Henslow’s theory of the origin of the various forms 
and structures of flowers as due to ‘ ‘ the responsive actions of the protoplasm 
in consequence of the irritations set up by the weights, pressures, thrusts, 
tensions, etc. , of the insect visitors ” ( The Origin of Floral Structures through 
Insect and other Agencies, p. 340). On the assumption that acquired char¬ 
acters are inherited, such irritations may have had something to do with 
the initiation of variations and with the production of certain details of 
structure, but they are clearly incompetent to have brought about the 
more important structural and functional modifications of flowers. Such 
are, the various adjustments of length and position of the stamens to bring 
the pollen to the insect and from the insect to the stigma ; the various 
motions of stamens and styles at the right time and the right direction ; 
the physiological adjustments bringing about fertility or sterility in hetero- 
styled plants ; the traps, springs, and complex movements of various parts 
of orchids ; and innumerable other remarkable phenomena. 
For the explanation of these we have no resource but variation and selec¬ 
tion, to the effects of which, acting alternately with regression or degradation 
as above explained (p. 328) must be imputed the development of the count¬ 
less floral structures we now behold. Even the primitive flowers, whose 
initiation may, perhaps, have been caused, or rendered possible, by the 
irritation set up by insects’ visits, must, from their very origin, have been 
modified, in accordance with the supreme law of utility, by means of varia¬ 
tion and survival of the fittest. 
