342 Supposed Connection of 



entirely different from that of the rest of the county. It has 

 been already mentioned that the flora of this county is more 

 alike to that of Edinburgh than to the Devonshire flora ; 

 while, on the other hand, I am inclined to believe that, were 

 a complete comparison made, the plants of the last-named 

 situation would be found to come nearer to those of the 

 second than to the Aberdeenshire species. Our rocks, how- 

 ever, have been stated to be more similar to those of Devon- 

 shire than to the rocks around Edinburgh ; to which last, 

 indeed, they are utterly unlike, though the plants of the two 

 tracts have a great similarity. These circumstances I am 

 disposed to explain, simply by this county having, in point of 

 latitude and climate, a greater resemblance to the district 

 around Edinburgh than to Devonshire. 



These views might, with advantage, be prosecuted much 

 farther than I can at present carry them. I shall just add 

 that it is clear, did any decided connection subsist between 

 rocks and vegetables, it would be very easy to establish the 

 fact indisputably by a suitable list, as the main rocks of the 

 world are but few indeed. Let, therefore, those who advo- 

 cate such a connection produce a satisfactory catalogue of 

 the kind alluded to. There may be instances in their favour, 

 I admit : but are these more numerous than the exceptions 

 to every general rule ? 



It ought not, however, to be considered as certain, that a 

 small number of plants may not show a degree of predilec- 

 tion, or the contrary, for one or more rocks. This may be, in 

 some measure, the case with regard to limestone and serpen- 

 tine. It is probably true that lime favours the existence and 

 propagation of wild plants : and hence it may be explained 

 why fewer plants are often found on primitive tracts than 

 upon others, as lime is a very sparing ingredient in the oldest 

 rocks. In this way I am disposed to explain a part of our 

 inferiority in vegetable numbers ; limestone being more abun- 

 dant in the two other districts than it is in Aberdeenshire. 

 The difference may also be imputed, in some degree, to our 

 less genial climate: but, indeed, not a little of it may be 

 owing to the Aberdeenshire list being almost entirely the 

 result of my own observation, not always under the most 

 favourable circumstances; whereas, the other tracts have 

 been more fully investigated. It also deserves to be recoil 

 lected, that all the species found only in the alpine parts of 

 Aberdeenshire are excluded from the list. As to serpentine, 

 I have made the following observations upon a small elevated 

 tract in the parish of Strathdon, composed of this rock. 

 Not only is the rock itself uncommon in that quarter, but its 



