APPENDIX. 



185 



■• My friend, Dr. Mantell, has presented very interesting and instructive' views of petrifaction 

 in his ' Wonders of Geology ; ' to which excellent work I beg leave to refer you to supply the 

 deficiencies of this hasty letter. You will observe that he mentions instances of the petrifaction 

 of soft animal and vegetable tissues. Should it be objected to the theory which I have sug- 

 gested, that an incipient petrifying coat would invest the substance externally, and defend it 

 from further impregnation, it should be remembered that fluids easily permeate all vascular 

 cavities and cellular tissues to the very centre, and cany with them whatever they hold in 

 solution. 



" In the living tree cut down, and the amputated end of its trunk instantly immersed in a 

 colored fluid, the extreme twigs and leaves soon show that every part has been penetrated. The 

 vegetables of the coal-formation and the lignite of the tertiary are not included in the view above 

 presented, as they are not petrified, but are merely altered vegetable matter. 



" Col. Wailes, of Washington, near Natchez, has succeeded in bringing back fossil Mas- 

 • todon bones to a firm and persistent state, simply by immersing them in a strong solution of 

 glue ; thus restoring the gelatine which the waters and time had taken away. At his house I 

 have seen his specimens, now beautifully preserved: they were found there near the Mississippi. 

 Now, had there been mineralized matter present to make its way in, as the gelatine went out, 

 then these bones would have been mineralized ; and such are the Mastodon bones of Ava, on 

 the Irriwaddy. I have one which is heavy with iron. 



" The phosphate of lime of bones, being already mineral matter, becomes petrified when the 

 animal matter is removed, and inorganic material substituted. Still, it is possible that the phos- 

 phate of lime may itself be removed, as we do sometimes find bones silicified which would 

 require either the removal of the bony matter, and the substitution of silex, or the combination 

 of the latter with it. 



" Your Mastodon skeleton is not in the least mineralized, but appears to retain its gelatine, 

 which accounts for its firmness. 



" Yours very respectfully, 



" B. SILLIMAN. 

 " Dr. J. C. Warren." 



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