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regarded as having been. originally a created instinct. This gener- 
ally received view is become altogether untenable, since we know 
through Darwin that neither are the individual kinds of animals, as 
such, created, nor are their special instincts unalterable. We now 
know that all kinds of one class of animals spring originally from 
one common kind of stock, and that, like their other peculi- 
arities, their instincts also are subject to alteration and trans- 
formation through the powerful influence of the training of nature. 
As animals are placed under new and unaccustomed life-circum- 
stances, they adapt themselves to these, find new thoughts, make 
new inventions, acquire new instincts. Necessity is the mother of 
invention, and practice makes perfect. The hard battle for 
existence makes in fact everywhere and at all times such stringent 
demands on the impulse of self-preservation of animals, that they 
are just as much compelled to learn and work, as men are. It is 
not true, even though now-a-days it is often asserted to be the case, 
that beavers build their water-palaces, swallows their nests, bees 
their honeycombs always and everywhere after the same manner 
to-day as they did two thousand or eight thousand years ago. 
On the contrary, we know from the most reliable observation that 
even these most highly developed art-impulses are subject to vari- 
ations of really great importance, and adapt themselves to the 
advantageous circumstances of any individual locality. The last 
of the Mohicans of the beavers which survive even to-day here and 
there in Germany have adapted themselves to the police-regulations — 
of civilised life and no longer build those grand water-palaces as 
their forefathers did two thousand years ago. Whilst here in 
Europe the cuckoo lays her eggs in strange nests, in America she 
has not adopted that bad habit. Every experienced bee-master 
knows how the special customs of bees vary in manifold ways in 
different hives. It is universally known that nightingales, finches 
and other singing birds learn new melodies, appropriate by 
imitation new tunes, consequently change their musical instinct. 
And do we not observe quite palpably in our house-dogs, terriers, 
colleys, &c., how new and diverse instincts have been acquired by 
training, practice and habit ? 
