518 Dr. Mac Culloch on Vegetable remains 



flinty matter by deposition from water is a daily occurrence, there is 

 no reason to doubt that they may be specimens of plants now actually 

 existing. But it is also necessary to consider their geological connex- 

 ions before a full answer can be given to such a question. This is 

 unfortunately attended with considerable difficulty, as the greater 

 number of specimens are only to be found in the hands of lapidaries 

 and jewellers, in circumstances which render it impossible even to 

 trace the country from whence they have been brought, and much 

 less the geological situations in which they have occurred. I have only 

 one meagre fact to offer on this subject. I have said in the com- 

 mencement of this paper, that many of the specimens found at 

 Dunglas contain remains of vegetables. These specimens appear 

 to have been detached from a breccia inferior to the lowest sandstone, 

 of which a part is visible at St. Abb's Head, and which is probably 

 a portion of the extensive breccia found in so many parts of Scot- 

 land, interposed between the primitive rocks and the whole series 

 of floetz strata. These then contain remains of organized substances 

 of an epocha at least equally ancient with that in which the vegetable 

 remains found in the^of/z strata existed. As the species ascertained 

 by Daubenton have in all probability been preserved in recent for- 

 mations of chalcedony, so it is probable that those which I am now 

 describing have been preserved in the chalcedonies of former days. 



It is said that chalcedonies of this nature are found in the Dutchy 

 of Deux Fonts, in Siberia, and in other situations, but there is no 

 information sufficiently accurate respecting these on which to ground 

 any reasoning. I ought however, to add, that in many of the 

 Siberian specimens which are known to lapidaries by the name of 

 Moss agates, I liave ascertained by chemical means that the green 

 fibres consist of chlorite. 



It would indeed have been unpardonable not to have used the aids 



