1 1 8 THE HISTORY OF CREATION. 



Linnaeus. The artificial system differs essentially from the 

 natural one, in the fact that it does not make the whole 

 organization and the internal structure (depending upon the 

 blood relationship) the basis of classification, but only 

 employs individual, and for the most part external, charac- 

 teristics, which readily strike the eye. Thus Linnaeus dis- 

 tinguished his twenty-four classes of the vegetable kingdom 

 principally by the number, formation, and combination of 

 the stamens. In like manner he distinguished six classes 

 in the animal kingdom principally by the nature of the 

 heart and blood. These six classes were : (1) Mammals ; 

 (2) Birds ; (3) Amphibious Animals ; (4) Fishes ; (5) Insects ; 

 and (6) Worms. 



But these six animal classes of Linnaeus are by no means 

 of equal value, and it was an important advance when, at 

 the end of the last century, Lamarck comprised the first 

 four classes as vertebrate animals (Vertebrata), and put them 

 in contrast with the remaining animals (the insects and 

 worms of Linnaeus), of which he made a second main division 

 — the invertebrate animals (In vertebrata). In reality Lamarck 

 thus agreed with Aristotle, the father of Natural History, 

 who had distinguished these two main groups, and called 

 the former hlood-hearing animals, the latter bloodless 

 animals. 



The next important progress towards a natural system of 

 the animal kingdom was made some decades later by two 

 most illustrious zoologists, Carl Ernst Bar and George Cuvier. 

 As has already been remarked, they established, almost 

 simultaneously and independently of one another, the pro- 

 position that it was necessary to distinguish several com- 

 pletely distinct main groups in the animal kingdom, each of 



