CHAP. XX. THE TERMS " SPECIES" AND "RACE." 389 



studying their physiology and geographical distribution, and, 

 above all, in examining and describing fossil species, is so 

 vast, that the additions made to our knowledge probably 

 exceed all that was previously known; and what Lamarck 

 then foretold has come to pass; the more new forms have 

 been multiplied, the less are we able to decide what we mean 

 by a variety, and what by a species. In fact, zoologists and 

 botanists are not only more at a loss than ever how to define 

 a species, but even to determine whether it has any real 

 existence in nature, or is a mere abstraction of the human 

 intellect, some contending that it is constant within certain 

 narrow and impassable limits of variability, others that it is 

 capable of indefinite and endless modification. 



Before I attempt to explain a great step which has recently 

 been made by Mr. Darwin and his fellow-laborers in this 

 field of inquiry, I think it useful to recapitulate in this place 

 some of the leading features of Lamarck's system, without 

 attempting to adjust the claims of some of his contemporaries 

 (Geof^voy St. Hilaire in particular) to share in the credit of 

 some of his original sjjeculations. 



From the time of Linnaeus to the commencement of the 

 present century, it seemed a sufficient definition of the term 

 species to say, that "a species consisted of individuals all 

 resembling each other, and reproducing their like by genera- 

 tion." But Lamarck, after having first studied botany with 

 success, had then turned his attention to conchology, and soon 

 became aware that in the newer (or tertiary) strata of the 

 earth's crust there were a multitude of fossil species of shells, 

 some of them identical Avith living ones, others simply varie- 

 ties of the living, and which, as such, were entitled to be 

 designated, according to the oi"dinary rules of classification, 

 by the same names. He also observed that other shells 

 were so nearly allied to living forms, that it was difficult not 

 to suspect that they had been connected by a common bond 



