138 



BIOLOGY AND ITS MAKERS 



year that his essay referred to was published (1859) ap>pean 

 Darwin's Origin 0} Species. Agassiz, however, was never 

 able to accept the idea of the transformations of species. 



Linnaeus 



Mammalia 



Aves 



Amphibia 



Pisces 



Insecta 



(Including Crusta- 

 cea, etc.) 



Vermes 



(Including Mol- 

 lusca and all 

 lower forms.) 



Cuvier 



Vertebrata 

 (Embracing five 

 classes: Mam- 

 malia, Aves, Rep- 

 tilia, Batrachia, 

 Pisces.) 



Mollusca 

 Articulata 



Radiata. 



Von Siebold 



Vertebrata 



(Embracing five 



classes.) 



Mollusca 



Arthropoda 



Vermes 



r Zoophyta. . . 

 ' Protozoa 



Leuckart 



Vertebrata 



(Five classes.) 



Mollusca 

 Arthropoda 



Vermes 

 Echinoderma 

 Coelenterata 

 Protozoa 



Steps in Biological Progress from Linnaeus to Darwin 



The period from Linnanis to Darwin is one full of im- 

 portant advances for biology in general. We have considered 

 in this chapter only those features that related to changes in 

 the system of classification, but in the mean time the morpho- 

 logical and the physiological sides of biology were being ad- 

 vanced not v only by an accumulation of facts, but by theii 

 better analysis. It is an interesting fact that, although during 

 this period the details of the subject were greatly multiplied, 

 progress was relatively straightforward and by a series of 

 steps that can be clearly indicated. 



It will be of advantage before the subject is taken up in 

 its parts to give a brief forecast in which the steps of prog- 

 ress- can be represented in outline without the confusion 

 arising from the consideration of details. Geddes, in 189J 

 pointed out the steps in progress, and the account that follow 

 is based upon his lucid analysis. 



