1296 THE STORY OF THE UNIVERSE 



THE ANIMAL KINGDOM 

 THOMAS H. HUXLEY 



AS soon as the labors of anatomists had extended 

 over a sufficiently great variety of animals, it 

 was found that they could be grouped into separate 

 assemblages, the members of each of which, while 

 varying more or less in minor respects, had certain 

 structural features in common, and these common 

 morphological characters became the definition of 

 the group thus formed. The smallest group thus 

 constituted is a Morphological Species. A certain 

 number of species having characters in common, by 

 which they resemble one another and differ from all 

 other species, constitutes a Genus; a group of genera, 

 similarly associated, constitutes a Family; a group 

 of families, an Order; a group of orders, a Class; a 

 group of classes, a Sub-kingdom; while the latter, 

 agreeing with one another only in the characters in 

 which all animals agree, and in which they differ 

 from all plants, make up the Animal Kingdom. 



Linnaeus, living at a time when neither compara- 

 tive anatomy nor embryology can be said to have ex- 

 isted, based his classification of animals upon such 

 broad resemblances of adult structure and habit as 

 his remarkable sagacity and wide knowledge en- 

 abled him to detect. Cuvier and his school devoted 

 themselves to the working out of adult structure, 

 and the Leqons d'Anatomie Comparee and the Regne 

 Animal are wonderful embodiments of the results of 

 such investigations. But the Cuvierian system ig- 



