April, 1836. coral formations. 569 



germs could be disseminated, the problem is rendered far 

 more intelligible. Again, if the theory should hereafter be 

 so far estabhshed, as to allow us to pronounce that certain 

 districts fall within areas either of elevation or subsidencej'it 

 will directly bear upon that most mysterious question, — 

 whether the series of organized beings pecuhar to some 

 isolated points, are the last remnants of a former population, 

 or the first creatures of a new one springing into existence. 



Briefly to recapitulate. In the first place, reefs are formed 

 around islands, or on the coast of the mainland, at that 

 limited depth at which the efficient classes of zoophytes can 

 live; and where the sea is shallow, irregular patches may 

 likewise be produced. Afterwards from the eff"ects of a series 

 of small subsidences, encircling reefs, grand barriers, or lagoon 

 islands, are mere modifications of one necessary result. Se- 

 condly, it can be shown on the above views, that the inter- 

 tropical ocean, throughout more than a hemisphere, may be 

 divided into linear and parallel bands, of which the alternate 

 ones have undergone, within a recent period, the opposite 

 movements of elevation and subsidence. Thirdly, that the 

 points of eruption seem invariably to fall within areas sub- 

 ject to a propulsion from below. The traveller who is an 

 eyewitness of some great and overwhelming earthquake, at 

 one moment of time loses aU former associations of the land 

 being the type of sohdity, so will the geologist, if he believe 

 in these oscillations of level (the deeply-seated origin of which 

 is betrayed by their forms and vast dimensions), perhaps be 

 more deeply impressed with the never-ceasing mutability of 

 the crust of this our World. 



