446 
determine, whether this supposed law has been admitted upon false 
grounds ; or whether it results from that arrangement in the ever 
admirable ceconomy of nature, by which her multifarious operations 
are carried on, without any injurious interference with each other. 
That the latter is the case will, I trust, appear, from a slight 
attention to the following observations. 
No circumstance has ever been remarked which will authorize 
the supposition, that vegetable matter can be liable to the bitu- 
minous change, until deprived of all the energies of vegetable life. 
But roots, as is well known, long retain their vegetative powers 
after entire separation from their trunk. The trunk, indeed, soon 
ceases to live ; but the root will be found, after a long period, to be 
alive : feeding on its own juices, and at last terminating this mode 
of existence, by changing into a soft pithy substance, which soon 
resolves into vegetable earth (Vegetahilia terrijicata, Waller). Hence 
it appears, that, after separation from the bodies which they sup- 
ported, the roots of trees continue to possess those powers, which 
most strongly oppose the bituminous change; and when deprived 
of these powers, they have suffered such an exhaustion of their 
principles, that their resolution into almost mere earth speedily 
follows. 
It is observed by Liebknecht, when speaking of the ferruginous 
tree found in Laubac, that, although the greatest care and industry 
was employed, only very few pieces were found which had the ap- 
pearance of roots ; and even these, he acknowledges, bore very few, 
if any, decided marks of having originally existed in that state*. 
PI. VI. Fig. 27, and 2Q, represent two substances, the latter of 
which has been supposed to have been the spine of an Echinus ; 
but careful examination shews that they are both parts of small 
branches or twigs of some tree. The substance represented at 
♦ Discursus de Diluvio maximo, &c. a Jo. Georgio Liebknecht, cap. iii. sec. 22, p. 283. 
