56 THE OCEAN WORLD. 
silent but incessant combat is being carried on—Z/fe, which builds 
up, and death, which pulls asunder. At first, life is all powerful—it 
lords it over matter; but its reign is limited. Beyond a certain 
point its physical vigour becomes gradually impaired ; with old age 
it feebly struggles ; and it is finally extinguished with time, when the 
chemical and physical laws seize upon it, and its organisation is 
destroyed. But in turn the very elements, though inert at first, are 
soon reanimated and occupied with a new life. Every plant, every 
animal is bound up with the past, and is part of the future, for every 
generation which starts into life is only the corollary upon that which 
expires, and the prelude of another which is about to be born. Life 
is the school of death ; death is the foster-mother of life. 
Life, however, does not always exhibit itself at the actual moment 
of its formation. It is visible later, and only after other phenomena. 
In order to develop itself a suitable medium must be prepared, and 
other determinate physical and chemical conditions provided. The 
presence and diffusion of living beings are by no means due to 
chance ; they follow rigorously an order of law. Speaking of the 
higher forms of animal life, the Duke of Argyll says (‘The Reign of 
Law”) :—‘‘In all these there is an observed order in the most rigid 
scientific sense, that is, phenomena in uniform connection and mutual 
relations which can be made, and are made, the basis of systematic 
classification. These classifications are imperfect, not because they 
are founded on ideal connections where none exist, but only because 
they fail in representing adequately the subtle and pervading order 
which binds together all living things.” 
The knowledge of extinct forms of animals and plants has thrown 
great light upon the regular and progressive development of organisa- 
tion. ‘The evolution of living beings seems to have commenced with 
the more rudimentary forms; the more ancient rocks, until very 
recently, had revealed no traces of life, and what has been lately 
revealed tends to confirm this view. In the Cambrian rocks of Bray 
Head, county Wicklow, the O/dhamia antigua is found—it is a form 
of very simple organisation; and the Rhizopods (Zoz00n canadense) 
found in the otherwise Azoic rocks of Canada is among the lowest 
forms of organised beings. It is only in beds of comparatively recent 
formation that we meet with animals of the higher classes. When 
plants first show themselves, even among these the simplest forms 
have priority. The combinations of life, at first simple, have become 
more and more complex, until the creation of man, who may be 
considered the masterpiece of organisation. 
If we expose a quantity of pure water to the light and air in the 
