QO VICTOR E. SHELFORD. 



open situations such as prairies and roadsides, where the physical 

 conditions are similar. Some animals of the same species which 

 make up the black oak community were taken from a roadside 

 and after being mixed with the inhabitants of the shrubs of the 

 beech forest, were placed in a light gradient. Soon the insects 

 and spiders of the two communities separated sharply from each 

 other, the beech-inhabiting species going to the darkest end while 

 the roadside species all crowded to the light. 



B. Later Communities. 



With the coming in of red oak true forest with the mineral 

 soil largely covered with humus and leaves is present and very 

 different mores obtain. The diurnal diggers are practically 

 absent. Snails, beetles, grasshoppers, spiders and myriopods 

 living under bark, decaying wood, and leaves, avoiding strong 

 light and requiring moisture, are the chief types. The mores 

 are typically forest in character. The differences between these 

 and the later stages are those of detail and degree which need 

 careful study. In general with a lessening in the severity of the 

 conditions, there is a proportional increase in the use of the vegeta- 

 tion as a place of abode. 



In the field and shrub strata, we note that the animals of the 

 cottonwood, pine and oak stages are characteristic of open dry 

 situations, requiring or tolerating strong light, while those ani- 

 mals of the red oak, hickory and beech stage are negatively 

 phototactic to light of the same intensity, as shown by mixing 

 the animals in a gradient. 



The animals of the tree stratum are few and scattered in the 

 cottonwood, pine and black oak stage while animals enclosed in 

 galls or cases are common if not dominant. In the red oak, 

 hickory and beech stage phytophaga are often gregarious and 

 numerous. The vegetation is used more and more for a breeding 

 place as the forest increases in denseness. Groups such as 

 orthoptera, beetles, bees and wasps, are represented more and 

 more by species which make use of the vegetation as forest 

 development goes on. The tree strata of all the forest stages 

 are characterized by species given to frequenting a limited number 

 of kinds of trees. 



