XXIII. On Vegetable remains preserved in Chalcedony. 



By J. Mac CuLLOcii, M.D. Chemist to the Ordnance, and Lecturer on 



Chemistry at the Royal Military Academy at Woolwich. 



v. Pr. Geo. Soc. 



iN examining the agates which are found on the shore at Dunglas 

 In Scotland, in the summer of ISll, I was struck with the appear- 

 ance of organized vegetable substances contained In many of them4 

 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 cir- 

 cumstances 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 va- 

 rieties 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 prin- 

 cipal 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 



* Momoircs de I'Academic Royale cles Sciences, 1782, p. 668. 



