334 LAMARCK, HIS LIFE AND WORK 
constitute all the acts of zzstinct; and as these acts 
are not the result of deliberation, of choice, of judg- 
ment, the actions which arise from them always 
satisfy, surely and without error, the wants felt and 
the propensities arising from habits. 
“Hence, zzstzzct in animals is an inclination which 
necessitates that from sensations provoked while 
giving rise to wants the animal is impelled to act 
without the participation of any thought or any act 
of the will. 
“This propensity owes to the organization what 
the habits have modified in its favor, and it is excited 
by impressions and wants which arouse the organic 
sense of the individual and put it in the way of send- 
ing the nervous fluid in the direction which the pro- 
pensity in activity needs to the muscles to be placed 
in action. 
“T have already said that the habit of exercising 
such an organ, or such a part of the body, to satisly 
the needs which often spring up, should give to the 
subtile fluid which changes its place where is to be 
operated the power which causes action so great a 
facility in moving towards this organ, where it has 
been so often employed, that this habit should ina 
way become inherent in the nature of the individual, 
which is unable to change it. 
‘“‘ Moreover, the wants of animals possessing a ner- 
vous system being, in each case, dependent on the 
structure of these organisms, are: 
“1, Of obtaining any kind of food; 
“9, Of yielding to sexual fecundation which excites 
in them certain sensations; 
“3. Of avoiding pain ; 
o va Of seeking “pleasure or happiness. 
“To satisfy these wants they contract different 
kinds of habits, which are transformed into so many 
propensities, which they can neither resist nor change. 
From this originate their habitual actions, and their 
