16 THE IMPORTANCE OF BIED LIFE 



tinual guard with brier hook and scythe, a hedge 

 invariably does spring into being along the fence 

 line. Almost before he realizes it, there will 

 arise a well defined row of junipers, choke- 

 cherries, sassafras, a conglomeration of a dozen 

 species perhaps, and banked by dense growth of 

 blackberries, wild raspberries, or sumacs. As 

 none of these spring from wind-blown seeds, 

 birds must be the carrying agents, or, if it be a 

 stone fence, chipmunks, perhaps, and birds. 



Again, certain plants owe their very existence 

 to the agency of birds. To the fruit-pigeons is 

 attributed the spread of wild nutmegs over New 

 Guinea and the -surrounding islands. The pig- 

 eons swallow the fruit for the sake of the red 

 "mace" which covers the seed, and later throw 

 out the hard pellet through the mouth as robins 

 do cherry-pits, or expel it with their f eces. 



A more striking example of entire dependence 

 is the case of the mistletoe. Living only as a 

 parasite on trees, the seed must be deposited in 

 a crevice of bark before the plant can develop. 

 The white viscous berries are eaten only by birds, 

 who later evacuate the seeds freed of pulp. If 

 this occurs while the bird is perched in a tree, the 

 excrement runs down over the branch and the 

 seeds find a lodgment for later germination. 



Further distribution of plant life may occur 

 from the mud which sometimes adheres to the feet. 

 Such an eventuality is particularly prevalent 



