220 THE HISTORY OF CREATION. 
influences of the surrounding outer world, assumes certain 
new peculiarities in its vital activity, composition, and form 
which it has not inherited from its parents; these acquired 
individual qualities are opposed to those which have been 
inherited, or, in other words, those which have been trans- 
mitted to it from its parents or ancestors. On the other 
hand, we call Adaptability (Adaptabilitas), or Variability 
(Variabilitas), the capability inherent in all organisms to 
acquire such new qualities under the influence of the outer 
world. (Gen. Morph. ii. 191.) 
The undeniable fact of organic adaptation or variation is 
universally known, and can be observed at every moment in 
thousands of phenomena surrounding us. But just because 
the phenomena of variation by external influences appear so 
self-evident, they have hitherto undergone scarcely any 
accurate scientific investigation. To them belong all the 
phenomena which we look upon as the results of contracting 
and giving up habits, of practice and giving up practices, or 
as the results of training, of education, of acclimatization, of 
gymnastics, etc. Many permanent variations brought about 
by causes producing disease, that is to say, many diseases, 
are nothing but dangerous adaptations of the organism to 
injurious conditions of life. In the case of cultivated plants 
and domestic animals, variation is so striking and powerful 
that the breeder of animals and the gardener found their 
whole mode of proceeding upon it, or rather upon the inter- 
action between these phenomena and those of Inheritance. 
It is also well known to every one that animals and plants, 
in their wild state, are subject to variation. Every syste- 
matic treatise on a group of animals or plants, if it were to 
be quite complete and exhaustive, ought to mention in every 
