174 The Study of Animal Life part m 



tree of life. These exceptional Protozoa are loose colonies 

 of cells, descendants or daughter- cells of a parent unit, 

 which have remained persistently associated instead of 

 going free with the usual individualism of Protozoa. They 

 illustrate to some minds a primitive co-operation of cells ; 

 they show us how the Metazoa or multicellular animals may 

 have arisen. 



3. The Parts of the Animal Body. — The physiologist 

 investigates life or activity at different levels, passing from 

 his study of the animal as a unity with habits and a tem- 

 perament, to consider it as an engine of organs, a web of 

 tissues, a city of cells, or finally as a whirlpool of living 

 matter. So the morphologist investigates the form of the 

 intact animal, then in succession its organs, their component 

 tissues, the minuter elements or cells, and finally the struc- 

 ture of the living stuff itself. Moreover, as there is no real 

 difference between studying a corpse and a fossil, the palae- 

 ontologist is also among the students of morphology ; and 

 most of embryology consists of studies of structure at dif- 

 ferent stages in the animal's life-history. 



The outer form of normal animals seems to be always 

 artistically harmonious. It has a certain hardly definable 

 crystalline perfection which pleases our eyes, but those who 

 have not already perceived this will not see much meaning 

 in the assertion, nor in Samuel Butler's opinion that " form 

 is mind made manifest in flesh through action." 



' ' I believe a leaf of grass is no less than the journey-work of the 



stars, 

 And the pismire is equally perfect, and the grain of sand, and 



the egg of the wren, 

 And the tree-toad is a chef-d'oeuvre for the highest, 

 And the running blackberry would adorn the parlours of heaven, 

 And the narrowest hinge in my hand puts to scorn all machinery, 

 And the cow crunching with depressed head surpasses any statue, 

 And a mouse is miracle enough to stagger sextillions of infidels ! " 



Walt Whitman. 



It is also important to think of the different kinds of 

 symmetry, how for instance the radiating sea-anemones and 

 jellyfishes, which are the same all round, differ markedly 



