234 LAMARCK, HIS LIFE AND WORK 
ences, became preserved and were propagated by 
generation.* 
“The bird which necessity (desotz) drives to the 
water to find there the prey needed for its subsist- 
ence separates the toes of its feet when it wishes to 
strike the water + and move on its surface. The skin, 
which unites these toes at their base, contracts in this 
way the habit of extending itself. Thus in time the 
broad membranes which connect the toes of ducks, 
geese, etc., are formed in the way indicated. 
‘But one accustomed to live perched on trees 
has necessarily the end of the toes lengthened and 
shaped in another way. Its claws are elongated, 
sharpened, and are curved and bent so as to seize the 
branches on which it so often rests. 
‘“‘ Likewise we perceive that the shore bird, which 
does not care to swim, but which, however, is obliged 
(a besoin) to approach the water to obtain its prey, 
will be continually in danger of sinking in the mud, 
but wishing to act so that its body shall not fall into 
the liquid, it will contract the habit of extending and 
lengthening its feet. Hence it will result in the gen- 
erations of these birds which continue to live in this 
manner, that the individuals will find themselves 
raised as if on stilts, on long naked feet; namely, 
denuded of feathers up to and often above the 
thighs. 
‘‘T could here pass in review all the classes, all the 
orders, all the genera and species of animals which 
exist, and make it apparent that the conformation 
of individuals and of their parts, their organs, their 
* Lamarck by the word génération implies heredity. He nowhere 
uses the word hérédité. 
{ ‘‘ L’oiseau que le besoin attire sur l’eau pour y trouver la proie 
qui le fait vivre, écarte les doigts de ses pieds lorsqu’il veut frapper 
eau et se mouvoir a sa surface” (p. 13). If the word veut has sug- 
gested the doctrine of appetency its meaning has been pushed too 
far by the critics of Lamarck, AN Ty auaie 
