138 
SELF-PRESERVATION. 
tendency to run away, but all do not fly with the same promptitude. Never¬ 
theless, in reflecting on the conduct of all animals, I saw that this action was 
general, that in some species it was more striking than in others, and that if it 
was less apparent in tame animals, the difference was to be attributed to the 
influence of external circumstances in diminishing the activity of this faculty so as 
to render it difficult to recognise its manifestations. Let us attempt, for exam¬ 
ple, to seize in its cage a bird which we have possessed only for a short time, 
and we shall be astonished at the efforts which it will make to escape; after an 
interval of time, more or less extensive, this animal, which at first took to flight 
at the slightest movement, will come and present itself to any person who wishes 
to take hold of it. 
Being nearly certain that there exists in animals an instinctive sentiment or 
faculty which prompts them to self-preservation, or to shun every thing that 
threatens their existence, it only remained to determine what might be the cere¬ 
bral part which was the seat of this feeling. 
The examination of the skulls of a great many animals was of no use, because, 
as has been already remarked, it was necessary that observations should be made 
first on individuals of the same species. I therefore devoted all my attention to 
the examination of the skulls of the Rabbits which I had observed with so much 
care. The skull of the Rabbit which took to flight with such rapidity, compared 
with the skulls belonging to two others of the same litter which allowed me to 
approach them readily, did not, at the first inspection, offer anything remarkable 
to my observation. It was not so with their brains. Viewed on the upper sur¬ 
face, these three brains differed very little, one excepted, in which the cerebellum 
was more developed. The case was very different when the base of the brain 
was examined. There was a striking difference in this region, between the brain 
of the Rabbit which had been the subject of my observations and the other two. 
In it, the proportion of the brain, A.A., plate Ixxvii, fig. 1, (in the Traite^ was 
twice as large as in the other brains. 
As I had particular reasons for preserving untouched four of the nine other 
Rabbits, I could examine only five more brains, and I did not find a single one 
the size of which, in the part before indicated, equalled that of the Rabbit which 
fled so fast on my approach. 
Immediately after making this observation, I carefully examined the brains of 
all the animals which I had preserved in spirits of wine, and also their skulls at 
the situation where this cerebral organ is placed. It was easy to do this on the 
base of skulls of the very numerous species which composed my collection. It 
would be difficult to convey an idea of the pleasure I experienced in discovering 
that all the animals which naturally have a tendency to fly with rapidity at the 
approach of any one, or by the influence of external circumstances, were precisely 
