29 INTRODUCTION. 
edifices, agreeably to the rules of the highest geometry, and destined to 
lodge and nourish a posterity not even their own. ‘The solitary bee, and 
the wasp also, form highly complicated nests, in which to deposit their eggs. 
From this egg comes a worm, which has never seen its parent, which is ig- 
norant of the structure of the prison in which it is confined, but which, once 
metamorphosed, constructs another precisely similar. 
The only method of obtaining a clear idea of instinct is by admitting the 
existence of innate and perpetual images or sensations in the sensorium, 
which cause the animal to act in the same way as ordinary or accidental 
sensations usually do. It is a kind of perpetual vision or dream that al- 
ways pursues it, and it may be considered, in all that has relation to its 
instinct, as a kind of somnambulism. 
Instinct has been granted to animals as a supplement to intelligence, to 
concur with it, and with strength and fecundity, in the preservation, to a 
proper degree, of each species. 
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 propor- 
tion 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 general, we have 
now to ascertain what are the essential characters in animals, on which 
their primary divisions are to be founded. It is evident that they should 
be those which are drawn from the animal functions, that is, from the sen- 
sations and motions; for both these not only make the being an animal, 
but in a manner establish its degree of animality. 
Observation confirms this position by shewing that their degrees of de- 
velopement and complication accord with those of the organs of the vege- 
tative 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 sce 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 di- 
gestion are simple excavations in the homogeneous 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 repre- 
sent so many brains, corresponds to a body divided into numerous rings, 
supported by pairs of limbs longitudinally distributed, &c. 
This correspondence of general forms, which results from the arrange- 
ment of the organs of motion, the distribution of the nervous masses, and 
