156 DEATH. 
action of these ministers of death. ‘Their species, rapidly growing 
rarer and rarer, are the memorials, the evidences of an anterior stage 
of the globe in which the inferior life swarmed, while nature laboured 
to purge the excessive fecundity. 
We can retrace in thought the scale of the successive necessities 
of destruction which the earth was thus constrained to undergo. 
Against the irrespirable air which at first enveloped it, vegetables 
were its saviours. Against the suffocating and terrific density of 
these lower vegetable forms, the rough coating which encrusted it, 
the nibbling, gnawing insect, which we have since execrated, was the 
sanitary agent. Against the insect, the frog, and the reptile mass, 
the venomous reptile proved an useful expurgator. Finally, when 
the higher life, the winged life, took its flight, earth found a barrier 
against the too rapid transports of her young fecundity in the power- 
ful voracious birds, eagles, faleons, or vultures. 
But these useful destroyers have diminished in numbers as they 
have become less necessary. The swarms of small creeping animals 
on which the viper principally whetted his teeth having wonderfully 
thinned, the viper also grows rare. The world of winged game being 
cleared in its turn, either by man’s depredations or by the disappear- 
ance of certain insects on which the small birds lived, you see that 
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the odious tyrants of the air are also decreasing; the eagle is seldom 
met with, even among the Alps, and the exaggerated and_enor- 
