138 BIOLOGY AND ITS MAKERS 
year that his essay referred to was published (1859) appeared 
Darwin’s Origin of Species. Agassiz, however, was never 
able to accept the idea, of the transformations of species. 
Linnzus Cuvier Von Siebold Leuckart 
Mammalia Vertebrata Vertebrata Vertebrata 
A (Embracing five (Embracing five (Five classes.) 
ves classes: Mam- classes.) 
Amphibia malia, Aves, Rep- 
P tilia, Batrachia, 
Pisces Pisces.) 
Insecta Mollusca Mollusca Mollusca 
(Including Crusta- js Arthropoda 
iculata..... Arthropoda 
cea, etc.) Articulata Vermies P 
Wevnies Vermes 
e Echinoderma 
aad . Zoophyta.... | 
(Including Mol Radiata....... ( oe Ccelenterata 
lusca and all ’ 
lower forms.) Protozoa Protozoa 
STEPS IN BIOLOGICAL PROGRESS FROM LINNEZUS TO DARWIN 
The period from Linneus 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 by 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. Geddes, in 1898, 
pointed out the steps in progress, and the account that follows 
is based upon his lucid analysis. 
