960 Influence of circumstances on the Actions of Animals. 
ON THE INFLUENCE OF CIRCUMSTANCES ON THE 
ACTIONS AND HABITS OF ANIMALS, AND 
THAT OF THE ACTIONS AND HABITS 
OF LIVING BODIES, AS CAUSES 
WHICH MODIFY THEIR 
ORGANIZATION. 
BY J. B. P. A. LAMARCK, ! 
Pe question here is not one of reasoning, but the examination 
of a positive fact, which is more general than is thought, and 
to which people have neglected to give the attention which it merits 
without doubt because, often, it is very difficult to recognize. This 
fact consists in the influence exercised by circumstances on the dif- 
ferent living bodies, which find themselves subjected to them. In 
fact, the influence of different states of our organism on our char- 
acter, our inclinations, our actions, and also our ideas, has been long 
remarked ; but it seems to me no one yet has recognized what influ- , 
ence our actions and our habits have upon our organization itself 
Now, as these actions and these habits depend entirely upon the 
circumstances in which we habitually find ourselves, I will attempt 
to point out how great is the influence which circumstances exercise 
on the general form, on the condition of parts, and thus upon the 
organization of living bodies. It is this very certain fact which is 
the question discussed in this chapter. 
If we had not had numerous opportunities to recognize clearly 
the effect of these influences on certain living bodies which we have 
placed in altogether new circumstances, and very different from those 
to which they were accustomed, and if we had not seen the effects 
and changes which have resulted, exhibiting themselves in many 
ways, under our eyes, the important fact in question would always 
have remained unknown to us. 
The influence of circumstances manifesting itself in bodies pos- 
sessing life, is effectual in all time and everywhere; but that which 
renders this influence difficult for us to perceive, is that these effects 
1 Constituting the Chap. VII., Vol. I., of the Philosophie Zodlogique. 
Translated for the American Naturalist by Dr. Eleanor E. Galt, from 
the edition of 1809. 
