INTRODUCTION. 29 
There is no visible mark of instinct in the conformation of 
the animal, but, as well as it can be ascertained, the intelligence 
is always in proportion to the relative size of the brain, and 
particularly of its hemispheres. 
Of Method, as applied to the Animal Kingdom. 
From what has been stated with respect to methods in ge- 
neral, we have now to ascertain what are the essential charac- 
ters in animals, on which their primary divisions are to be 
founded. It is evident they should be those which are drawn 
from the animal functions, that is from the sensations, and mo- 
tions; for both these not only make the being an animal, but in 
a manner establish its degree of animality. 
Observation confirms this position by showing that their 
degrees of development and complication accord with those of 
the organs of the vegetative functions, 
The heart and the organs of the circulation form a kind of 
centre for the vegetative functions, as the brain and the trunk 
of the nervous system do for the animal ones. Now we see 
these two systems become imperfect and disappear together. 
In the lowest class of animals, where the nerves cease to be 
visible, the fibres are no longer distinct, and the organs of. 
digestion are simple excavations in the honogeneous mass of > 
the body. In insects the vascular system even disappears 
before the nervous one; but, in general, the dispersion of the 
medullary masses accompanies that of the muscular agents: a 
spinal marrow, on which the knots or ganglions represent so 
many brains, corresponds to a body divided into numerous’ 
rings, supported Wy pairs of limbs longitudinally distributed, 
&e. ith as £ mt p 
This correspondence of cane forms, which feagie from ~ 
the arrangement of the organs of motion, the distribution of the 
neryous masses, and the energy of the circulating system, 
should then be the basis of the primary divisions of the animal 
‘kingdom. We will afterwards ascertain, in each of these 
divisions, what char acters should succeed immediately to those, 
and form the basis of the primary subdivisions. 
