

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-labourers 

 in this field of enquiry, 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 con 

 temporaries (GreofFroy St. Hilaire in particular) to share in 

 the credit of some of his original speculations. 



From the time of Linnaeus to the commencement of the 

 present century, it seemed a sufficient definition of the term 

 species to say, that c 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 with living ones, others simply 

 varieties of the living, and which, as such, were entitled to 

 be designated, according to the ordinary rules of classifica 

 tion, 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 



