46 
fashion ; and so on for yet another g< enerath on.' Or, of 
oWnce of nails, accompanied with perfect baldness 
oarriS down through four generations , or 
down through five generations. Or, again of deal-dumbness, 
transmitted'through four generations ; of albinoism Z 
alterations in the eye, snarly hereditary E s pecia y do 
such instances prove the wonderful power KZence 
inheritance. At every successive reproduction, the influe 
of the original variant diminished by one hal£ so that by tbe 
fourth generation it amounted only to one- tbirty-se com 3 by 
the fifth generation only to one sixty-fourth part ol the total 
Yet so Zng » ^ ‘eefcoey to 
variations even when, as m these examples, of a highly dis- 
advantageous or even abortive character, that, notwithstanding, 
the peculiarity still made its appearance. In a similai way 
the hereditary character of structural diseases, as consumption, 
t . I acknowledged hy all These then 
where we may say everything was against the «herrtance ot 
the variation, and yet it was inherited. Had the ^nations 
been beneficial, and so themselves have tended L to P^ ser 
vation— had, for example, the palmation 01 the toes occurred 
in a bird living partly in the water, or the baldness in anothei 
to whom headlfeathers were inconvenient (and the like pheno- 
menon has been observed to be hereditary in doves); or, again, 
had similar changes taken place, only m an opposite direction, 
—say the strengthening of the lungs instead « their weaken- 
ing or the addition of pigment to eyes formerly devoid of it, 
inftead of its withdrawal from eyes formerly possessed of it 
had especially, owing to the favourable mfluei^ 
variations and the consequent multiplication of their pos 
session some of the successive generations been torn of 
parents' both, of whom varied in the same manner;, bad this 
been so we cannot doubt but that races of living beings would 
S come into existence differing most markedly m structure 
from their progenitors, and forming species which the anti- 
Darwinian natmalist would ridicule the idea of ever having 
mirnnef from tfie source they did. 1 
' P Then, in the next place, it must he observed that sucb 
tions extend also to notable differences connec ed with habit 
and manner of growth. Thus no one will dispute the maikea 
physiological distinction between a tree that sheds dsleavesui 
the autuhm and regains them in the spring, and another that 
retains 'its'leaves all the year round. The internal system 01 
ruertreesTs manifestly widely different. Yet we have an 
example of a tree, the plane-tree, occasionally varying hv be- 
coming evergreen. One such in the island of Crete was famous 
