LAMARCK'S THEORY OF EVOLUTION 24I 



Modification of the organization from one end 

 to the other of the animal chain. 



" One is forced," he says, " to recognize that the 

 totality of existing animals constitute a series 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. -j 



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 series which constitutes the animal scale re- 

 sides in the distribution of the groups, and not in 

 that of the individuals and species. 



" I have already said * that by this shaded gradua- 

 tion in the complication of structure I do not mean 



* Systime des Animaux sans Verthbres, pp. 16 and 17. 

 16 



