60 THE MAIN CURRENTS OF ZOOLOGY 



the larger groups of animals will be helpful at this 

 point. 



LINN.EUS 

 Mammalia (Mammals) 



Aves (Birds) 



Amphibia (Amphibia 



and Reptiles) 

 Pisces (Fishes) 

 Insecta (Including 



Crustacea, etc.) 

 Vermes (Including 



Mollusca and all 



lower forms) 



CUVIER 



Vertebrata (Embracing 

 five classes: Mam- 

 malia, Aves, Rep- 

 tilia, Batrachia, Pis- 

 ces) 



Mollusca 

 Articulata . 



Radiata . 



VON SIEBOLD 



Vertebrata 

 (Embrac- 

 ing five 

 classes) 



Mollusca 



f Arthropoda 

 \ Vermes 



f Zoophyta 

 [ Protozoa 



LEUCKART 



Vertebrata 

 (Five 

 classes) 



Mollusca 



Arthropoda 

 Vermes 



f Echinoderma 

 \ Ccelenterata 



Protozoa 



Biological progress (outside the changes in classi- 

 fication) from Linnaeus to Darwin, although details 

 were greatly multiplied, proceeded by definite steps. 

 Linnaeus and his successors were concerned with the 

 organism as a whole, the external appearance, colors, 

 spots, the horns, the hoofs, etc. The next distinct 

 step was that taken by Cuvier and his school. In- 

 stead of the complete organism, the organs of which 

 it is composed became the chief subject of analysis. 

 The organism was dissected, the organs were exam- 

 ined and those of one kind of animal were compared 

 with another. This started the line of comparative 

 anatomy which played a much more important part 

 in the development of zoology than work of the 

 Linnaean type. After the organs were investigated 

 the tissues came under review and, then, with more 



