68 HUXLEY 



structure. Towards the close of that century, 

 Linnaeus had completed his great scheme of classifica- 

 tion of plants and animals, dividing the latter into six 

 classes : the Vertebrates into mammals, birds, am- 

 phibians (including reptiles), and fishes ; and the 

 Invertebrates into insects and worms. Aristotle had 

 conceived of life as a ladder whose steps represented 

 the several animals in ascending scale : Lamarck (to 

 whom Huxley pays high tribute *), with genuine in- 

 sight, depicted it as a many-branched tree, and there- 

 fore, as interrelated and interdependent. Cuvier re- 

 duced Linnaeus's six divisions to four : Vertebrata, or 

 backboned (fishes to men) \ Mollusca, or soft-bodied 

 (snails, oysters, etc.) ; Articulata, or jointed (spiders, 

 bees, ants, etc.), and Radiata, or rayed (jelly-fish, 

 polyps, sea-anemones). 



Meanwhile, the microscope, by which, in the mid- 

 dle of the seventeenth century, Malpighi had made 

 pioneer discoveries, was becoming more and more the 

 important instrument of examination of the internal 

 structure of living things, and hence opening the way 

 to inquiry into their origin and history. The study 

 of anatomy advanced to comparison of the structures 

 and of the several corresponding organs in divers 

 plants and animals, and of the functions discharged 

 by those organs; hence the rise of the comparative 



1 n. 59- 



