result of silex injected in a state of igneous fusion. I know not that it is necessary for the theory which offers this explanation, that this solution should be admitted, since the existence of that theory is not necessarily implicated in the universal proof of this supposition. It will scarcely be asserted that substances of so tender a structure as those I have described, substances so evidently involved in siliceous matter while freely exposed to light and air, could have undergone this change by any process of compression connected with igneous fusion. Nor could any theorist invent a scheme of this nature which should involve the remains of a land animal, so fragile as is that chrysalis of an insect figured in the plate No. 29, with so little change of structure. A watery solution of silex seems so indispensable for this purpose, that it is superfluous to insist upon it. Of such watery solutions there are abundant examples existing, examples which it is unnecessary to quote; but the instances under examination offer to our consideration views still more wide and more interesting, however difficult their explanation may be. It is plain on reviewing some of the cases above described, that a process different from the tedious one of infiltration and gradual deposition, must have produced the appearances in question. Neither the free disposition nor the forms of the delicate vegetable structures could have been preserved during so slow a process, nor could their colour have remained unaltered The loss of colour must have followed the death of the plant, and the total loss of its figure would have resulted from the gradual changes which it must needs have undergone during the continuance of a process so tedious. The remains are in fact (if I may use such an expression) embalmed alive. To produce this effect, we can only conceive a solution of silex in water, so dense as to support the weight of the substance involved, a solution capable of
