FIG. i. CROSS-SECTION OF VERTEBRATE (A) 

 AND INVERTEBRATE (B). 



CONSTITUTION OF THE ANIMAL AND PLANT KINGDOMS. 39 



childhood ; and it serves, moreover, to indicate very cursorily indeed 

 the scientific and further delineation of the animal constitution. 

 Lamarck, whose name is associated with views concerning the 

 transformation and evolution of species, contributed a very decided 

 addition to the knowledge of the constitution of the animal world, 

 when, about the close of last century, he showed that the beasts, 

 birds, reptiles, and fishes, instead of being regarded as distinct and 

 unconnected divisions of animals, might be grouped together to 

 form a large and characteristic 

 division of the kingdom. He 

 pointed out that each and all 

 of these animals, as he knew 

 them, possessed, firstly, a spine 

 or backbone. Within this spine 

 (Fig. i, A p x ), whereof the skull 

 formed merely a front expansion, 

 the nervous system ( 2 ) was con- 

 tained as within a tube ; whilst 

 below that system, and contained 

 within the body (/ 2 ) itself (as bounded, say, by the ribs), were the 

 heart (//), digestive system (a), and other organs. Lamarck, com- 

 menting upon this arrangement of parts which a glance at the 

 carcase of a sheep, as vertically bisected in the butcher's shop, will 

 illustrate demonstrated that no other animals, save mammals, birds, 

 reptiles, and fishes, possessed such a disposition of their organs. The 

 worm or the insect, for instance, possesses a body (Fig. i, B) we may 

 legitimately compare with the lower tube (A) of the fish or beast, 

 since neither the worm nor insect has a spine containing a nervous 

 system. Hence Lamarck, taking his chief character from the spine 

 or backbone, composed of separate bones or vertebra, named the 

 beasts, birds, reptiles, and fishes the Vertebrata, whilst all other 

 animals became accordingly known as Invertebrata. 



That Lamarck's discovery and his subsequent arrangement of 

 the animal world into these two leading divisions marked a distinct 

 era in zoology no one can doubt. Best of all, his deduction laid the 

 foundation of the method which a little later that is, about 1795 

 Cuvier so successfully enunciated and followed out to a practical 

 result. Other hands, in addition, laboured at the scientific edifice, 

 which was practically completed when Cuvier laid before the world 

 his elementary scheme of the history of animals, and showed that at 

 least three common types or plans could be instituted amongst the inver- 

 tebrate animals. Placed in tabular order, then, the main outlines 

 of the animal world, according to Cuvier, might be thus rendered : 



I. VERTEBRATA ( " backboned " animals) (fishes, frogs, reptiles, 

 birds, and mammals). 



