OBGANIZATION OF LAND COMMUNITIES 51 



animals such as the white-footed mice appear to 

 be present in greater abundance than they were a 

 century ago. It is worth repeating that with the 

 decrease in the larger carnivores that fed on 

 squirrels and on deer, the latter became more 

 abundant; with further decrease in the number of 

 powerful predators, the smaller competing preda- 

 tory forms, notably the foxes, raccoons and skunks, 

 increased in numbers. 



In fertile areas the advance of the white man 

 has meant the practical disappearance of the 

 forest and of its accompanying plant and animal 

 life. Unfortunately this disappearance came be- 

 fore many of the more complicated problems of 

 the organization of animal communities could be 

 studied and, obviously, the solving of such prob- 

 lems can be undertaken still more imperfectly 

 at the present time than a century or more ago. 

 Such studies are being carried on in the available 

 splinters of the former forest and in the much less 

 broken Canadian woods. Among the forest 

 fragments that have been much studied are two 

 small tracts that lie near the state university of 

 Illinois. These include a bit of low-lying wood- 

 land with its characteristic growth of elm and 

 maple trees and a neighboring parcel on higher 

 ground with maple and red oak as dominants. 



In such forest communities, the trees are the 



