28 PEOCEEDINGS OF THE 



distinguistablo by invariable characters ; and the old idea of the 

 duration of species from the beginning is readily disproved by 

 the naturalists who study the treasures of the museum." 



" Everybody," he says, " knows how difFicult it is to recognize 

 or to determine species, on account of the existence of races and 

 varieties wliich merge, shade by shade, into neighbouring 

 species." 



" Species only have a constancy relational to the duration of the 

 circumstances under which the individuals liave lived. Many 

 genera of plants and animals are of such magnitude, on account 

 of the number of species, that the study and distinction of the 

 species are almost impi'acticable. The species of these large 

 genera arranged in series and allied by their structures shuw 

 such slight differences -with those which could be placed next to 

 them, that they merge and shade into each other ; and thus the 

 species become, as it were, more confounded. The isolated spe- 

 cies only exist because the gaps between them are not yet filled 

 up." " I do not," Lamarck continues, " assert that animals form 

 a simple series, everywhere equally intersliading ; but I would 

 say that the series is a branching one, gradating irregularly, and 

 which has no discontinuity in its parts, or which, at least, has 

 not always been discontinuous ; for there are lost species to 

 account for." 



"A mass of facts," he says, " teach us that when individuals of 

 a species change their localities, climate, and habit of living, they 

 are influenced thereby, and change little by little in the con- 

 sistence and proportion of their parts, shape, and organization, 

 so that every part participates, in time, in the mutation. Simple 

 vari'.ition of individuals is produced, at first, under varying condi- 

 tions under the same climate ; but in long periods these con- 

 stant vicissitudes operate upon succeeding generations, and lead 

 to structural and necessary distinctions. After many genera- 

 tions, the individuals w^hich were once in one species would find 

 tliemselves transformed into another and distinct one." Lamarc-k 

 wrote that he perceived the importance of a method in Nature 

 which consists in preserving in newly reproduced individuals all 

 that the results of life and its conditions have prodiiced in the 

 orqanization of the ancestral forms. 



The influence of hybridity and the ability of hybridization to 

 perpetuate species is denied. He disposes of the arguuunt 

 against variability used by certain naturalists in consequence of 

 M. Greofl'roy's Egyptian collection showing no specific changes. 

 He states that the conditions have not altered, and therefore the 

 forms have remained as they w^ere. He adds : — " But we may 

 rest assured that this appearance of stability of things in 

 Nature will always be taken- ' par le vnlgaire des hommes ' as 

 a reality, because in general they only judge from personal 

 experience." 



Lamarck did not recognize life to be any thing else than a 

 natural process. He speculated ou the probability of sponta- 



