CHASTER : SPECIES AND VARIATION. 21 



As naturalists we are constantly speaking and writing about 

 species, so that it surely behoves us to gain as clear an idea as 

 possible of what the word really signifies. Let us first consider 

 what ideas have held currency. 



^Ve may take Linnseus as the pioneer of all systematic biological 

 work and as the first to recognize in a really comprehensive manner 

 the idea of species from a scientific standpoint. To Linnseus, as 

 in a more or less definite form to his predecessors, a species repre- 

 sented the direct descendants of certain original prototypes that had 

 been produced by special creation. Throughout all the successive 

 generations each species had retained and reproduced its original 

 distinctive characters. This theory of special creation was of course 

 based upon the cosmogonies contained in the first two chapters of 

 Genesis. We do not propose to undertake any laboured con- 

 sideration of this theoretical idea, which prevailed long after the 

 days of Linnaeus. 



Let us look at a few definitions of the word that have been given in 

 more recent times. Huxley in the Smithsonian Reports for 1869 

 defines a species as " the smallest group to which distinctive and 

 invariable characters can be assigned." A very casual examination 

 will show that this definition is valueless. In Helix nemoralis L., 

 for example, each " band formula " constitutes a group to which 

 distinctive and invariable characters can be assigned, and yet these 

 groups cannot be looked upon as worthy of more than a minor 

 varietal rank. 



In the " Century Dictionary " there is given this definition of the 

 word as used in biology : — "that which is specialized or differentiated 

 recognizably from anything else of the same genus, family, or order; 

 an individual, or collectively, those individuals which differ specifically 

 from the other members of the genus, etc. ; and which do not differ 

 from one another in size, shape, colour and so on, beyond the limits 

 of (actual or assumed) variabiUty, as those animals and plants which 

 stand in the direct relationship of parent and offspring, and 

 perpetuate certain inherited characters intact or with that little 

 modification which is due to conditions of environment." I have 

 no intention of taking a definition so prolix as this for a text upon 

 which to base my remarks upon species. But it is worthy of note 

 that even this definition is largely based upon a series of assumptions 

 each of which in certain cases may be found incapable of demonstra- 

 tion. The limits of variability in a species are stated to be actual or 

 assumed. How are we to ascertain these limits if they actually exist, 

 and if they are merely assumed how are we to ensure the reasonable- 

 ness of the assumption? Again, the members of a species stand in 

 the relationship of parent and offspring according to this definition. 



