26 
II. 
ON THE TENDENCY OF VARIETIES TO 
DEPART INDEFINITELY FROM THE 
ORIGINAL TYPE.* 
Instability of Varieties supposed to prove the permanent 
distinctness of Species. 
One of the strongest arguments which have been ad- 
duced to prove the original and permanent distinct- 
ness of species is, that varieties produced in a state of 
domesticity are more or less unstable, and often have 
a tendency, if left to themselves, to return to the 
normal form of the parent species; and this insta- 
bility is considered to be a distinctive peculiarity of 
all varieties, even of those occurring among wild 
animals in a state of nature, and to constitute a pro- 
vision for preserving unchanged the origmially created 
distinct species. 
In the absence or scarcity of facts and observa- 
tions as to varieties occurring among wild animals, 
this argument has had great weight with natural- 
ists, and has led to a very general and somewhat 
* Written at Ternate, February, 1858; and published in 
the Journal of the Proceedings of the Linnzan Society for 
August, 1858. 
