56 THE OCEAN WORLD. 



silent but incessant combat is being carried on — life, 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 ph}sical 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 w^hich 

 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 throAATi 

 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 Oldhamia aiitiqua is found — it is a form 

 of very simple organisation ; and the Rhizopods {Eozoon 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 



