- positions, and the mere putting together and separating objects more or
less alike."[*]
Before proceeding to open the philosophical discussion which inevitably arises on the mention of Mr. Darwin's book, I will here set down the chief groups, according to Cuvier's classification, for the benefit of the tyro in natural history, who will easily remember them, and will find the knowledge constantly invoked.
There are four Sub-kingdoms, or Branches:—1. Vertebrata. 2. Mollusca. 3. Articulata. 4. Radiata.
The VERTEBRATA consist of four classes:—Mammalia, Birds, Reptiles, and Fishes.
The MOLLUSCA consist of six classes:—Cephalopoda (cuttlefish), Pteropoda, Gasteropoda (snails, &c.), Acephala (oysters, &c.), Brachiopoda, and Cirrhopoda (barnacles).—N.B. This last class is now removed from the Molluscs and placed among the Crustaceans.
The ARTICULATA are composed of four classes:—Annelids (worms), Crustacea (lobsters, crabs, &c.), Arachnida (spiders), and Insecta.
The RADIATA embrace all the remaining forms; but this group has been so altered since Cuvier's time, that I will not burden your memory just now with an enumeration of the details.
The reader is now in a condition to appreciate the general line of argument adopted in the discussion of Mr. Darwin's book, which is at present exciting very great attention, and which will, at any rate, aid in general culture by opening to many minds new tracts of thought. The benefit in this direction is, however, considerably lessened by the extreme vagueness which is commonly attached to the word "species," as well as by the great want of philosophic culture which impoverishes the majority of our naturalists. I have heard, or read, few arguments on this subject which have not impressed me with the sense that the disputants really attached no distinct ideas to many of the phrases they were uttering. Yet it is obvious that we must first settle what are the facts grouped together and indicated by the word "species," before we can carry on any discussion as to the origin of species. To be battling about the fixity or variability of species, without having rigorously settled what species is, can lead to no edifying result.
It is notorious that if you ask even a zoologist, What is a species? you will almost always find that he has only a very vague answer to give; and if his answer be precise, it will be the precision of error, and will vanish into contradictions directly it is examined. The consequence of this is, that even the ablest zoologists are constantly at variance as to specific characters, and often cannot agree whether an animal shall be considered of a new species, or only a variety. There could be no such disagreements if specific characters were definite: if we knew what species meant, once and for all. Ask a chemist, What is a salt? What an acid?
- DARWIN: Origin of Species, p. 420.
