10 THE AMERICAN BOTANIST. 



of plant lice and fungi so that the extent of the damage can- 

 not be estimated for several years to come. 



The most interesting feature of the cicada work was the 

 very noticeable fact, that, though the ground was covered 

 with injured branches, and the trees generally hung full of 

 them, some trees were not injured at all! The forest of 

 Arden near Joliet, 111. gave an excellent chance to investigate 

 this fact of the immunity of certain species. The Forest is a 

 three-hundred acre piece of oak and maple woods in which 

 other trees are naturally interspersed. It has been woods 

 ever since the glacial epoch, to go back no farther. The 

 seventeen-year cicada has laid its eggs on these trees and 

 their ancestors through all of that time. Anyone who heard 

 their constant singing during the month of June, would make 

 no question as to the numbers of individuals, and the proba- 

 bility of their finding and using every available place in which 

 to deposit eggs. Nor would there be any doubt that any 

 species not used by the wives of these drummers was exempt 

 because of some quality inherent in its own being. 



Another reason why the Forest afforded an excellent 

 means for testing this question, lay in the manner of its 

 planting. While the foundation is a native woodland, the 

 botanical planting has been arranged along the five miles of 

 drives, laid out for landscape purposes; and the planting has 

 been done with the object always in view of keeping the 

 natural wild appearance in predominance. So the planted 

 trees and shrubs are surrounded on all sides by native trees 

 and shrubs growing where the ancestors of these cicadas left 

 them seventeen years ago. 



To be explicit, if I have a plantation of about twenty-five 

 species of evergreens, interspersed with gooseberries, dog- 

 woods, ash and willows, and I find these native trees and 

 shrubs ripped almost to pieces, and find only one slit on one 



