LAMARCK’S THEORY OF DESCENT 349 
order of origin of the invertebrate classes, Lamarck 
proposes a new genealogical tree. He states that the 
order of the animal series “is far from simple, that it 
is branching, and seers even to be composed of 
several distinct series;’’ though farther on (p. 456) 
he adds: 
“Je regarde f’ordre de la production des animaux 
comme Cas de deux séries distinctes. 
“ Ainsi, je soumets a la méditation des zoologistes 
l’ordre a tee de la Jormation des animaux, tel 
que l’exprime le tableau suivant : 
In the matter of the origin of instinct, as in evolu- 
tion in general, Lamarck appears to have laid the 
foundation on which Darwin’s views, though he 
throws aside Lamarck’s factors, must rest. The “in 
herited habit ” theory is thus stated by Lamarck. 
Instinct, he claims, is not common to all animals, 
since the lowest forms, like plants, are entirely pas- 
sive under the influences of the surrounding medium ; 
they have no wants, are automata. 
“But animals with a nervous system have wazts, 
z.e., they feel hunger, sexual desires, they desire to 
avoid pain or to seek pleasure, etc. To satisfy these 
wants they contract habits, which are gradually trans- 
formed into so many propensities which they can 
neither resist nor change. Hence arise habitual 
actions and special propensities, to which we give the 
name of zustznct. 
“These propensities are inherited and become in- 
nate in the young, so that they act instinctively 
from the moment of birth. Thus the same habits 
and instincts are perpetuated from one generation to 
another, with no wotadle variations, so long as the 
