VITALITY OF BURIED VEGETABLE GERMS. 259 



down before the superincumbent tree had commenced its 

 growth. In other instances, the relative positions of trees 

 and stumps are such that we are compelled to assign to 

 perfectly sound timber, retaining even its characteristic ar- 

 omatic odor, an antiquity of hundreds and even of thou- 

 sands of years. (See Cook, Geology of New Jersey, 1868, 

 p. 343, etc. ; Lyell, Second Visit to the United States, vol. 

 i.,p.34.) 



Buried tree-trunks are often exhumed from glacial drift 

 at the depth of twenty to sixty feet from the surface. Dr. 

 Locke has published an account of a mass of buried drift- 

 wood at Salem, Ohio, fifteen miles north of Dayton, where 

 it lies from thirty-seven to forty-three feet beneath the sur- 

 face, imbedded in a layer of ancient mud. The museum of 

 the University of Michigan contains several fragments of 

 well-preserved tree-trunks exhumed from wells in the vicin- 

 ity of Ann Arbor. Such occurrences are by no means un- 

 common. The encroachments of the waves upon the 

 shores of the "great lakes" reveal whole forests of the 

 buried trunks of the White Cedar {Thuja occidentalis), 

 bearing scarcely a trace of the work of destructive agencies 

 upon them. 



Unaltered vegetable structures have been found in geo- 

 logical deposits of even higher antiquity. It is known that 

 well-preserved woody tissue has been frequently exhumed 

 from deposits of Tertiary, and even of greater age. I am 

 in possession of pieces of drift-wood from the Cretaceous 

 sands of Alabama, in which the ligneous tissue is so fully 

 preserved as to be capable of ignition, like recent wood. 

 Even from the Coal Measures of Michigan I have made 

 preparations of the delicate tissues of the fronds of so- 

 called Scale-mosses (Jungermanniacece) ; and from the coal 

 mines of Lasalle, in Illinois, I have collected specimens of 

 exogenous wood of a brown color and not yet carbonized, 



