LAMARCK’S THEORY OF DESCENT 333 
performing certain intelligent acts, it is still more 
often the inner feeling and the inclinations origi- 
nating from habits which decide, without choice, the 
acts which animals perform. 
‘* Moreover, although the executing power of move- 
ments and of actions, as also the cause which directs 
them, should be entirely internal, it is not well, as has 
been done,* to limit to internal impressions the 
primary cause or provocation of these acts, with the 
intention to restrict to external impressions that 
which provokes intelligent acts; for, from what few 
facts are known bearing on these considerations, we 
are convinced that, either way, the causes which 
arouse and provoke acts are sometimes internal and 
sometimes external, that these same causes give rise 
in reality to impressions all of which act internally. 
“ According to the idea generally attached to the 
word zustinct the faculty which- this word expresses 
is considered as a light which illuminates and guides 
animals in their actions, and which is with them what 
reason is to us. No one has shown that instinct can 
be a force which calls into action; that this force 
acts effectively without any participation of the will, 
and that it is constantly directed by acquired inclina- 
tions.” 
There are, the author states, two kinds of causes 
which can arouse the inner feeling (organic sense)— 
namely, those which depend on intellectual acts, and 
those which, without arising from it, immediately ex- 
cite it and force it to direct its power of acting in the 
direction of acquired inclinations. 
“These are the only causes of this last kind, which 
* Richerand, Physiologie. vol ii. p. 151. 
