340 LAMARCK, AIS LIFE AND WORK 
flanks, and with those which connect the tail with 
the two hind feet, forming in these animals great 
membranous wings with which they fly perfectly, as 
everybody knows. 
“Such is then the power of habits, which have a 
singular influence on the conformation of parts, and 
which give to the animals which have for a long time 
contracted certain of them, faculties not found in 
other animals. 
“As regards the amphibious animals of which I 
have often spoken, it gives me pleasure to communi- 
cate to my readers the following reflections which 
have arisen from an examination of all the objects 
which I have taken into consideration in my studies, 
and seen more and more to be confirmed. 
“T do not doubt but that the mammals have in 
reality originated from them, and that they are the 
veritable cradle (derceau) of the entire animal king- 
dom. 
“‘ Indeed, we see that the least perfect animals (and 
they are the most numerous) live only in the water ; 
hence it is probable, as I have said (vol. ii., p. 85), that 
it is only in the water or in very humid places that 
nature causes and still forms, under favorable con: 
ditions, direct or spontaneous generations which have 
produced the simplest animalcules and those from 
which have successively been derived all the other 
animals, 
“We know that the Infusoria, the polyps, and the 
Radiata only live in the water; that the worms even 
only live some in the water and others in very damp 
places. 
“Moreover, regarding the worms, which seem to 
form an initial branch of the animal scale, since it is evi- 
dent that the Infusoria form another branch, we may 
suppose that among those of them which are wholly 
aquatic—namely, which do not live in the bodies of 
other animals, such as the Gordius and many others 
