.128 



WHAT IS A SPECIES ? 



By 



L. C. H. Young, b.a.., f.b.s., &c. 



There is* no question, I suppose, more often asked the well-informed 

 naturalist by an amateur than " What is a species?" Nor is there 

 tiny probably which so often meets with an unsatisfactory reply. 



Of course " the short answer which turneth away wrath" is that 

 it is the unit of classification, but this as a rule hardly satisfies the needs 

 of the inquirer, and moreover in these days of " subspecies, " named 

 varieties aud ' ' races " is in danger of being no longer true. 



So confused has the problem become that a distinguished entomo- 

 logist in a recent work has declined to use the word at all and calls 

 . all his units " forms. "" 



The question really should be put in another way, " Is a species a 

 : natural division or is it a convention of systematists ? " 



Previous to the publication of the " Origin of Species, " the existence 

 ran nature of the species was not seriously called in question, the belief 

 in the separate creation of each form being general. 



Darwin himself had a very clear notion of what he meant by a 

 species, though like every one else he found it difficult to frame a 

 definition in anything but Gladstonian language, — that is to say, in 

 a form which was not capable of varied interpretation according to the 

 predilections of the individual systematise 



Since Darwin's time however many naturalists have affected to 

 ignore the problem on the ground that since it had been proved that 

 all nature was in a state of constant flux there was obviously no such 

 thing as finality in forms or terminal developments, and that a 

 "species" as a unit in the natural kingdom was a superstition of the 

 ancients. As a corollary to this, species being merely convenient 

 conventions it was open to every man to multiply or divide them 

 . according to his own notions of convenience. 



This kind of convenience lias generally proved a great inconvenience 

 to practical collectors and economic and field naturalists. 



This is specially the case with tropical creatures. For instance no 

 one with any knowledge of the Lepidoptera would have any hesitation 

 in identifying a specimen of Arctia caja (the Common Tiger Moth), 

 although it is a most variable insect, and it would be possible in one 



