Species

Species, the unit of classification for animals and plants - that is, a collection of individuals (or specimens) that make up a genus. So long as naturalists held the doctrine of fixity of species, there was no difficulty in framing a definition of the term, for the dictum of Linne was generally accepted that there were as many species as the Infinite Being had created forms in the beginning." This, if true, would fix the origin of species and from this it followed that a species was a gronp of organisms, descended from a pair divinely created, possessing similar characters, and capable of reprodncing organisms like themselves. Lamarck, in the early part of the 19th century, suggested that specles were subjective, and not objective; but the influence of Linne prevailed, and it was not till the publication of the Origin of Species in 1859 tbat the Linnean conception was replaced by the theory of Evolution. Since that date, though the term "species" is retained as a convenient one for a group of individuals agreeing in essential characters which can be transmitted to their descendants, it is recognised that it is incapable of strict drfinition, and that what one naturalist would class as a species another would class as a mere variety, while a third would possibly give it generic rank. Professor E. Ray Lankester, in his article Zoology in the Encyclopaedia Britannica, says that "Species, as well as genera, orders, and classes, are the subjective expressions of a vast ramifying pedigree, in which the only objective existences are individuals." The truth of this will be evident on consideration; and if proof were needed, it would be afforded by a comparison of the classifications of different naturalists, especially in those dealing with the lower forms of life. There is comparatively little difficulty in separating the larger animals into species, but the nearer one gets to the base of the genealogical tree the more hopeless does the task become of drawing with a firm hand the dividing line between species and variety, so closely do many of the forms approach their neighbours on each side.