THE WILD MAMMALS OF THE FARM 99 
Then there are a few little insect-eating mammals, like the 
moles and the shrews in their burrows in the soil, and the bats 
in the air, that perhaps are not greatly affected by the 
changed conditions. Southward, there is the interesting 
_ marsupial, the opossum, nocturnal, wary and elusive, holding 
its own. 
The group of mammals includes those animals that are 
most like us in structure and habits and mode of develop- 
ment. Among them are our best servants, our best pro- 
ducers of bodily comforts, our most direct competitors and 
our most dangerous enemies. We have gathered the more 
docile of those useful to us about our homes, and have made 
them our more immediate servants. We have exploited their 
untamable allies to the limit of our powers. So long as there 
remained a toothsome body or a prized pelt, we spared not. 
Our enemies and competitors we killed. At first it was done 
in self-defense: of late, it has been done in sheer and wanton 
love of slaughter. Improved weapons of destruction have 
placed the larger beasts completely at our mercy, and we have 
had no mercy. There remain with us one that we avoid, a 
few that are too small to be deemed worthy of pursuit, and a 
few that are able to elude us. At our approach the squirrels 
hide from us in the trees; the gophers and their kind drop 
into their burrows, the swamp-dwellers slip into the water, 
and the wily foxes watch us from the thickets. Eternal 
vigilance is the price of their safety. We may see little of 
them when we walk in the woods or by the streamside, but 
there are many pairs of sharp little eyes always watching us. 
Before the final disappearance of the larger species, it is 
well that we are taking measures to keep a remnant of them , 
in game preserves: our descendants will want to know what 
the native fauna of their native land was like. Wedo well, 
also, to consider that each species we destroy isa final product 
of the evolution of the ages. It is the outcome of the toil and 
