Influence of circumstances on the Actions of Animals. 965 
pared with those animals of the race from which they came. Who 
does not know that any bird of our climate which we have raised 
in a cage, and which has lived there five or six years, continuously, 
when liberated is not able to fly as its kind who have always been 
free? This trifling change of circumstance acting on this individ- 
ual, has in truth only diminished its faculty of flight, and without 
doubt has made no change in the form of the parts of the individ- 
uals, But if successive generations of individuals of the same 
race had been held in captivity during a considerable time, there is 
no doubt that even the form of the parts would little by little have 
undergone notable changes. A stronger reason yet, if instead of a 
simple captivity maintained in regard to them, this citcumstance 
has been for some time accompanied by a change of very different 
climate, and that these individuals by degrees had been habituated 
to other kinds of food, and to other movements to get it, certainly 
these circumstances united and become constant would have formed 
insensibly a new race altogether peculiar. Where is found now in 
nature the multitude of races of dogs which, in consequence of the 
domestication to which we have reduced them, have been brought 
into the condition in which they are at present? Where are found 
the bulldogs, greyhounds, spaniels and lapdogs, etc., races which 
show in themselyes greater differences than those which we would 
admit as specific among animals of the same genus living at liberty 
in nature? 
Without doubt a first and unique race, first cousin of the wolf, 
if not himself the true type, has been some time tamed and domes- 
ticated by man. This race, which showed at that time no differ- 
ence among the individuals, has been gradually dispersed with man 
into different countries and into different climates, and after having 
long submitted to the influence of the places of habitation and the 
diverse habits which they have been made to contract in each coun- 
try, they have experienced remarkable changes and have formed 
peculiar races, Now man, for the sake of commerce or for other 
interests, travels great distances; and having transported into well- 
peopled places, as a great capital, different races of dogs bred in 
countries far apart, and then crossed them, he has by generation 
given origin successively to all these which we now know. 
The following fact proves, in regard to plants, how the change 
