C31") 
ago the original paper, I could not avoid thinking that some 
special explanation would hereafter be found for so curious a 
case. I speculated whether a species very liable to repeated 
and great changes of conditions might not assume a fluctuating 
condition ready to be adapted to either conditions.” * 
I venture to express the prediction that this class of cases, 
already very numerous, will hereafter be immensely enlarged, 
and will become especially important in the vegetable king- 
dom.+ Although Hooker at one time took the opposite side, 
and thought that plants were never ‘‘changed materially by 
external conditions—except in such a coarse way as stunting 
or enlarging,” { Darwin considered that “ physical conditions 
have a more direct effect on plants than on animals.” § Un- 
doubtedly the view at the time was that of Buffon, the idea of 
an operation of the environing forces almost as direct as 
those which produce the weathering of rocks or the whitening 
of an exposed flint. But it is probable that the more in- 
timately we know of the conditions of plant-life, the more 
fully it will be recognised that all such changes are adaptive. 
* ¢¢ More Letters,” vol. i, p. 391, Letter 303. 
+ See ‘‘Stimulus and Mechanism as Factors in Organisation” by J. 
Bretlend Farmer, F.R.S. (the New Phytologist, vol. ii, Nos. 9 and 10 
Novy. and Dee. 1903), Professor Farmer speaks of the probable prevalance 
in the plant-world of ‘‘a constant specific mechanism that is able to be 
actuated in different ways by different kinds of stimuli.” Although for 
the purpose of his paper Professor Farmer is concerned with the train of 
physico-chemical sequences which is set going, utility or no utility, when- 
ever the mechanism of an individual is stimulated, he fully admits that 
the mechanism itself has come to be a character of the species by the oper- 
ation of natural selection. ‘‘ Naturally,” he says, ‘‘only those species 
whose inner character expressed itself in making these ‘suitable’ adjust- 
ments to the environment were able to survive.” 
Toward the close of his paper Professor Farmer seems to bring the con- 
siderations that have regard to the species into somewhat unnecessary 
conflict with those that have regard to the individual. Thus he says 
that ‘‘current literature still teems with teleological ‘explanations that 
really explain nothing, but rather bar the way of scientific enquiry.” 
A properly loaded, well-constructed modern gun goes off, for disadvan- 
tage no less than for advantage, when its trigger is pulled ; but the very 
existence of the gun depends upon a long succession of past stages, each of 
which was more advantageous than its predecessor. The recognition of 
this history does not bar the way of enquiry, but rather stimulates and 
suggests a searching and intelligent study of the latest mechanism with 
all its intricacy. 
+ See the letter from Hooker to Darwin, March 17, 1862, in ‘‘ More 
-Letters,” vol. i, p. 197. 
§ See the letter from Darwin to Lyell [June 14, 1860], ‘Life and 
Letters,” vol. ii, p. 319. 
