282 LAMARCK, HIS LIFE AND WORK 



as that of sensation : she has had the means of pro- 

 ducing this faculty in the imperfect animals of the 

 first classes of the animal kingdom," referring to the 

 Protozoa. But she has accomplished this gradually 

 and successively. " Nature has progressively created 

 the different special organs, also the faculties which 

 animals enjoy." 



He remarks that though it is indispensable to 

 classify living forms, yet that our classifications are all 

 artificial ; that species, genera, families, orders, and 

 classes do not exist in nature — only the individuals 

 really exist. In the third chapter he gives the old 

 definition of species, that they are fixed and immu- 

 table, and then speaks of the animal series, saying : 



" I do not mean by this to say that the existing 

 animals form a very simple series, and especially evenly 

 graduated ; but I claim that they form a branched 

 series,* irregularly graduated, and which has no dis- 

 continuity in its parts, or which, at least, has not al- 

 ways had, if it is true that, owing to the extinction of 

 some species, there are some breaks. It follows that 

 the species which terminates each branch of the gen- 

 eral series is connected at least on one side with 

 other species which intergrade with it " (p. 59). 



* Lamarck's idea of the animal series was that of a branched one, 

 as shown by his genealogical tree on p. 193, and he explains that the 

 series begins at least by two special branches, these ending in branch- 

 lets. He thus breaks entirely away from the old idea of a continuous 

 ascending series of his predecessors Bonnet and others. Professor 

 R. Hertwig therefore makes a decided mistake and does Lamarck a 

 great injustice in his " Zoblogy," where he states: "Lamarck, in 

 agreement with the then prevailing conceptions, regarded the animal 

 kingdom as a series grading from the lowest prim.itive animal up to 

 man " (p. 26) ; and again, on the next page, he speaks of " the theory 

 of Geoffroy St.-Hilaire and Lamarck" as having in it " as a funda- 

 mental error the doctrine of the serial arrangement of the animal 

 world " (English Trans.). Hertwig is in error, and could never 

 have carefully read what Lamarck did say, or have known that he 

 was the first to throw aside the serial arrangement, and to sketch out 

 a genealogical tree. 



