Cn. IV.] PEOCESS OF PETRIFACTION. 43 



We liave still, however, mucli to learn before the conversion of fossil 

 bodies into stone is fully understood. Some phenomena seem to imply 

 that the mineralization must proceed with considerable rapidity, for 

 stems of a soft and succulent character, and of a most perishable nature, 

 are preserved in flint ; and there are instances of the complete silicifica- 

 tion of the young leaves of a palm-tree when just about to shoot forth, 

 and in that state which in the West Indies is called the cabbage of the 

 palm."^ It may, however, be questioned whether in such cases there 

 may not have been some antiseptic quality in the water which re- 

 tarded putrefaction, so that the soft parts of the buried substance may 

 have remained for a long time without disintegration, like the flesh of 

 bodies imbedded in peat. 



Mr. Stokes has pointed out examples of j^etrifactions in which the 

 more perishable, and others where the more durable portions of wood 

 are preserved. These variations, he suggests, must doubtless have de- 

 pended on the time when the lapidifying mineral was introduced. Thus, 

 in certain silicified stems of palm-trees, the cellular tissue, that most de- 

 structible part, is in good condition, while all signs of the hard woody 

 fibre have disappeared, the spaces once occupied by it being hollow or 

 filled with agate. Here, petrifaction must have commenced soon after 

 the wood was exposed to the action of moisture, and the supply of min- 

 eral matter must then have failed, or the water must have become too 

 much diluted before the woody fibre decayed. But when this fibre is 

 alone discoverable, we must suppose that an interval of time elapsed be- 

 fore the commencement of lapidification, during which the cellular tissue 

 was obliterated. When both structures, namely, the cellular and the 

 woody fibre, are preserved, the process must have commenced at an 

 early period, and continued without interruption till it was completed 

 throughout, f 



* Stokes, Geol. Trans. voL v. p. 212, second series, 

 f Ibid. 



