LAMARCK’S THEORY OF EVOLUTION 241 
Modification of the organization from one end 
to the other of the antmal chain. 
‘One ws torced, he says, “to: recopnize’ that the 
totality of existing animals constitute a serzes of 
groups forming a true chain, and that there exists 
from one end to the other of this chain a gradual 
modification in the structure of the animals compos- 
ing it, as also a proportionate diminution in the num- 
ber of faculties of these animals from the highest to 
the lowest (the first germs), these being without doubt 
the form with which nature began, with the aid of 
much time and favorable circumstances, to form all 
the others. 
He then begins with the mammals and descends to 
molluscs, annelids, and insects, down to the polyps, 
“as it is better to proceed from the known to the 
unknown ;” but farther on (p. 38) he finally remarks : 
“Ascend from the most simple to the most com- 
pound, depart from the most imperfect animalcule 
and ascend along the scale up to the animal richest 
in structure and faculties; constantly preserve the 
order of relation in the group, then you will hold the 
true thread which connects all the productions of 
nature; you will have a just idea of its progress, and 
you will be convinced that the most simple of its liv- 
ing productions have successively given existence to 
all the others. 
“The sertes which constitutes the animal scale re- 
sides in the distribution of the groups, and not in 
that of the tndividuals and species. 
“T have already said * that by this shaded gradua- 
tion in the complication of structure I do not mean 
* Systéme des Animaux sans Vertebres, pp. 16 and 17. 
16 
