138 



BIOLOGY AND ITS MAKERS 



year that his essay referred to was published (1859) appeared 

 Darwin's Origin oj 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 

 i Vermes 



( Zoophyta. 

 ' Protozoa 



Leuckart 



Vertebrata 

 (Five classes.) 



Mollusca 

 Arthropoda 



Vermes 

 \ Echinoderma 

 t Ccelenterata 



Protozoa 



Steps in Biological Progress from Linnaeus to Darwin 



The period from Linnauis 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 only by an accumulation of facts, but bv their 

 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. Geddcs, in 1898, 

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

 is based upon his lucid analysis. 



