Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/520



examining the agates which are found on the shore at Dunglas in Scotland, in the summer of 1811, I was struck with the appearance of organized vegetable substances contained in many of them. It seeming to me impossible that any metallic or earthy matter could put on these forms, I was at some trouble to make a collection of stones exhibiting similar appearances, and to ascertain as far as circumstances permitted, the genera at least of the plants contained in them. The gradual increase and ultimate accumulation of numerous specimens, having enabled me to trace their analogies to plants actually existing, I considered that a detail of the most leading varieties would not be unacceptable to the Society. For the purposes of a more accurate and convenient illustration than the inspection of the specimens alone would convey, I also transmit some enlarged drawings, made by the aid of the microscope, exhibiting the principal varieties.

I did not know when I was first engaged in this investigation that the subject had already attracted attention, and that a detailed account of some well ascertained plants involved in chalcedony had been given by Daubenton. More lately a letter from Blumenbach has