134 
THE PRINCIPLES OF BIOLOGY. 
Mr. Spencer lias, in the chapter now under notice, referred 
to attempts on the part of De Maillet and others, including 
Dr. Erasmus Darwin (father of Charles Darwin), and also 
Lamarck, to explain organic evolution by the assumption that 
each form of life is imbued with an inherent disposition to 
develop new and improve existing organs, with also the 
tendency to transmit to their progeny such organs more or 
less developed, with increased desires for greater complexity 
of organisation. 
Now, without any desire to ignore the facts of hereditary 
transmission of organs, whether rudimentary, developed, or 
even potential, it is only necessary to bear in mind the infinite 
variety of forms of life to perceive at once that such influ¬ 
ences are but factors in the problem, and important as they 
undoubtedly are, they are quite insufficient for our acceptance 
as an explanation of the resultant effects. Where the con¬ 
ditions of life are stationary, forms ot life are stationary also. 
Progress in organic development, either of kind or function, 
is not essential to vitality. 
There are many kinds of plants and animals which, under 
existing conditions, are doomed to that extinction which, in 
every direction, has overtaken forms of life which, like 
individual lives, can never reappear, but under the improbable, 
if not impossible, recurrence of exactly the same conditions 
under which they were developed and maintained. I have 
yet to learn that individual lives of apparently expiring forms 
of life show any decadence of vitality. The facilities for the 
extension of any form of life over a larger area, or an increase 
of numbers on a given area, may be increased or lessened 
without any consequent individual loss of vitality, such as 
would be indicated by shortened lives. There is a plant, well 
known to us all by the name of groundsel—I abstain from the 
use of botanical terms as I am too ignorant to inflict them 
upon you—which, because it gives us trouble, we call a weed; 
and which I believe is doomed to extinction on account of 
its propensity to fertilise itself with its own pollen. However 
much that propensity may hasten the time when from its 
rarity the saicLplant may, for its beauty, be deemed a flower 
and treated as such, individual plants flourish without any 
apparent or recorded diminution of vitality. 
The florist takes in hand an insignificant plant, and by 
skilful manipulation produces from it endless varieties of 
form and colour, none of which would have been produced 
but for the florist. 
By similar processes of selection, the flockmaster suppresses 
in the sheep that of which he disapproves, and developes 
that which he desires as dictated by fashion or requirement. 
