I 



1909] The Ottawa Naturalist. 69 



WHAT IS A "SPECIES"? 



By F. H. Wolley-Dod, Millarville, Alta. 



There is perhaps no word in the English language of which 

 the true meaning, as applied to living organisms, has been dis- 

 cussed at greater length than the word "species." Strictly- 

 speaking, of course, the word is a latin one, which has become 

 anglicized under what we believe to be its original form, or at 

 any rate as the Romans used it in the time of Julius Caesar, and 

 Ave shall find the same meaning given whether we look it up in 

 an English or a Latin Dictionary, viz., "a sort", or "kind", "an 

 aggregate of individuals". As a matter of fact the wholly un- 

 scientific man, "the man in the street" rarely uses the word at 

 all. He doesn't understand its meaning. "A kind", or "sort" 

 is expressive enough for him, and anyone can understand what 

 that means. But for the naturalist the third meaning here given, 

 "an aggregate of individuals" is the one which better expresses 

 his meaning when he talks of a "species". 



So long as we do not think too much about it that meaning 

 is "good enough, that is to say we use it to mean an individual 

 kind, an aggregate of individuals, as entirely distinct from another 

 individual kind or aggregate of individuals. He would be an 

 argumentative man indeed who would dispute the fact that an 

 oak was quite a distinct kind of tree from a fir, or that a pheasant 

 was quite a distinct bird from a duck, or, amongst animals, 

 a fox distinct from a bear. And most people will be quite willing 

 to admit that there are different kinds, or more technically, 

 "species", of oaks, firs, pheasants, ducks, foxes, and bears. That is 

 to say that there are certain aggregates of individuals or "species" 

 of each of the above named things that are more or less easily 

 to be distinguished from other aggregates of individuals of the 

 same class. That these kinds are to be distinguished each by 

 certain characters of colour, form, habit, etc., not possessed by 

 the other kinds is impHed by the use of the word "species". 

 NaturaHsts may tell us, for instance, that the grizzly bear is 

 quite distinct from the brown bear by the colour of its fur, the 

 shape of its head, the comparative size or shape of certain bones 

 in the body or limbs, habits of feeding, etc. Or botanists, that a 

 certain species of oak is distinguished from another by the shape 

 of its leaves or acorns, or the exact wav in which they grow from 

 the twigs, by the form of growth, or shape of the tree itself, by 

 the colour or texture of its wood, and in each case that these 

 characters are not possessed by any other species. But why 

 these kinds should -be considered separate because they differ 

 in these parts, or what degree of difference is necessary before 



