LIFE ON THE EARTH. 67 



ORIGIN OF LIFE ON THE EARTH. 



We have found by this mode of inquiry that the 

 abundance of the forms of life in the sea has been 

 very unequal at different periods, and that race has 

 followed race so as to match the words of the poet 



Augescunt alise gentes, aliae minuuntur, 



Inque brevi spatio mutantur ssecla animantum, 



Et quasi cursores vita'i lampada tradunt. 



Can we trace back this system to an origin, or do 

 we discover only cycles of perpetual change, system 

 following system, with 'no trace of a beginning, no 

 prospect of an end'? Perhaps the following consi- 

 derations will incline the reader to adopt the opinion 

 which ascribes a definite origin in time to life on 

 the earth. 



1. It is ascertained that, in passing downward 

 through the lower Palaeozoic Strata, the forms of 

 life grow fewer and fewer, until in the lowest Cam- 

 brian Rocks they vanish entirely. In the thick series 

 of these strata in the Longmynd (supposed to be 

 20000ft. thick or more) hardly any traces of life 

 occur. Yet these strata are of a kind such as might 

 be expected to yield them ; for they are not in general 

 peroxidated, nor conglomeritic, nor much affected 

 by metamorphic action, nor so much confused by 



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