336 Supposed Connection of 



Scotland. Dr. Murray found Rhodiola rosea, several years 

 ago, on the sea-side in Aberdeenshire ; where it had, upon the 

 land side of it, one of the most extensive plains in Scotland.] 



I have never had an opportunity of perusing this Maga- 

 gazine in a regular manner; but Major Youngson of this 

 county, a subscriber to it, having some time since obliged me 

 with a considerable collection of the recent Numbers, I observe 

 more than one notice of remarks formerly offered by me in 

 Jameson's Journal, with the view of endeavouring to prove 

 that native vegetables are not materially influenced by the 

 subjacent rocks. This circumstance has led me to think of 

 the present communication, wherein I shall aim at a more 

 satisfactory, though a shorter, consideration of the question, 

 than was offered in that place ; and, feeling an anxiety to arrive 

 at the truth, I venture to express a hope that some of the 

 numerous correspondents of this Magazine may be induced to 

 give their opinions upon a subject undoubtedly of an inter- 

 esting description ; on which there is a common tendency to 

 a conclusion which, in my estimation, is far from being well 

 supported. The question maybe stated as being — 



Whether or not vegetable species are usually determined by 

 the nature of the subjacent rocks f Or, in other words, Whe- 

 ther native plants spring up, and extend themselves, upon all rocks 

 indiscriminately ; or some only over one kind of rock, and others 

 only over anotjier? 



In the first place, I think it may be stated, that there are 

 only two very evident cases wherein plants can be influenced 

 by the nature of the mineral strata: 1st, when the vegetable 

 roots come into contact with these strata; and, 2d, when the 

 soil is wholly, or in a great measure, derived from the rock 

 beneath. Let us, therefore, endeavour to ascertain if those 

 conditions frequently exist. 



The distance of rocks from the surface differs greatly in 

 different instances. At Amsterdam, 230 ft. of soil have been 

 penetrated ; and upon the plains in the north of Germany 

 it is said that a rocky surface is never found. In short, 

 all degrees of depth are met with, from those just men- 

 tioned, to the bare rock upon which the humble lichen can 

 scarcely find a suitable abode. It may, however, be laid 

 down as a general rule, that, in the present day, rocks lie at 

 so great a depth that they cannot be reached by the roots of 

 vegetables. It is next to be considered, that, in numerous 

 instances, the soil is not derived from the subjacent solid 

 strata: as it will be admitted, that, when a proper opportunity 

 offers for making the observation, it is frequently apparent 



