DURABILITY OF WOODS 165 



which exhibited all the external features of that species, includ- 

 ing the characteristic color and fibrous bark (48, 562). When 

 cut with a saw the well-known odor was given off somewhat 

 freely. Under the microscope the structure was found to exhibit 

 no evidence of alteration, while there was seen to be only a 

 limited development of mycelial filaments, - - not as much as 

 may often be found in badly seasoned logs. This condition of 

 preservation is to be ascribed chiefly, no doubt, to the fact that 

 the wood was hermetically sealed in an impervious clay which 

 completely excluded all fungi and inhibited further growth of 

 those originally present. This explanation appears the more 

 probable from the fact that leaves of the Vallisneria spiralis, 

 embedded in the same clays, show all the details of the original 

 structure when freshly exposed, and it is only upon subsequent 

 dessication that disorganization takes place. 



Juniperus calif ornica from the interglacial deposits of Hum- 

 boldt County, California (46), offers a very similar though much 

 more instructive example of preservation through long periods 

 of time. This wood was obtained from two localities, in the one 

 case occurring in blue, sandy silt under one hundred and fifty 

 feet of local debris, while in the other case it was embedded 

 in blue, slaty muck under fifty to sixty feet of local debris. A 

 microscopic examination showed that the structure contains very 

 few mycelial filaments, in fact only slightly more than in the 

 Don specimen of Juniperus virginiana. The structure of the 

 tissues is well preserved and gives no evidence of that oblitera- 

 tion of parts which usually accompanies the operation of fungi 

 and bacteria, whence we may correctly infer that such organisms 

 were not operative. It was nevertheless found that the tissues 

 did not offer the normal amount of resistance to the action of the 

 knife in cutting sections, the result being a localized fragmenta- 

 tion. The material was only very slightly silicified and there was 

 no difficulty in the removal of the mineral matter, but the entire 

 structure presented unusual thickening of the cell walls, such 

 as would arise through the action of strong alkali. Alterations 

 of this character are not infrequent among fossil plants, most 



